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By J. J. S. Sebastian

The process development described in this report was carried out at the Morgantown Station of the U. S. Bureau of Mines in cooperation with West Virginia University. An experimental laboratory-scale pilot unit to gasify coal dust in entrainment was constructed on the Campus of the University in Morgantown. The enormously accelerated demand for liquid and gaseous fuels and utilization of our immense coal resources require that a low-cost process be developed for the gasification of a wide variety of coals. Such a process would be a major factor in lowering the cost of synthetic liquid fuels. None of the proc3sses developed in Germany prior to and during World War II, such as the Winkler process, the H. Koppers dust gasification process, the Wintershall-Schmalfoldt process, etc., meet all the requirements for a low-cost process under American conditions. Nor has any other process designed and experimentally operated at atmospheric pressure during the post-war period in this country appeared to fulfill all of the necessary conditions for a low-cost process.

Jan 1, 1950

By Brent A. Slaker, Michael Murphy, John Ellenberger, Erik Westman

"Photogrammetry, as a tool for monitoring underground mine deformation, is an alternative to traditional point measurement devices, and may be capable of accurate measurements in situations where technologies such as laser scanning are unsuited, undesired or cost-prohibitive. An underground limestone mine in Ohio is used as a test case for monitoring of structurally unstable pillars. Seven pillars were photographed during four visits over a 63- day period. Using photogrammetry, point clouds of the mine geometry were obtained and triangulated surfaces were generated to determine volumes of change over time. Pillar spalling in the range of 0.29–4.03 m3 of rock on individual rib faces was detected. Isolated incidents of rock expansion prior to failure, and the isolated failure of a weak shale band, were also observed. Much of the pillars remained unchanged during the monitoring period, which is indicative of proper alignment in the triangulated surfaces. The photographs of some ribs were of either too poor quality or had insufficient overlap, and were not included. However, photogrammetry was successfully applied to multiple ribs in quantifying the pillar geometry change over time.IntroductionAdequately measuring underground rock mass movements is integral to understanding how rock masses behave and how to interact with them safely and efficiently. Many modern measurement techniques employed in underground mining environments rely on point measurements, such as through extensometers or borehole relief methods (Christiansson, 2006). These techniques, while commonplace, do not provide a comprehensive view of how the rock mass is behaving. The dynamic changes in stress states underground, coupled with the mechanical uncertainty of rock masses, near active excavations, creates a need for measurement systems which better capture the behavior of the rock mass. Photogrammetry is a technology capable of producing the wide-area displacement measurements required for a comprehensive understanding of rock mass movements.Digital photogrammetry is a means of obtaining threedimensional point clouds from digital photographs. By finding the same point across multiple images, all viewing an object from different angles, the location of that point in three-dimensional space can be inferred. Close range digital photogrammetry (CRDP) is photogrammetry applied to measuring objects or scenes less than 100 meters away (Atkinson, 1996), and is used for various functions in underground mining environments. These uses include, but are not limited to, mapping fracture networks (Kim, Kim, & Won, 2005)(Somervuori & Lamberg, 2010), characterizing fractures (Styles et al., 2010) and measuring volumes of blast rock (Heal, Hudyma, & Potvin, 2004)."

Jan 1, 2015

By Walter S. Bergholz, Michael L. Schreder

"Since Escondida began operations in fiscal 1991, a series of aggressive expansion projects have enabled market share to be increased and ever larger profits to be realized. This was possible due to the very large size of the ore body and its high grade - averaging 2.7% copper from startup through fiscal 1997. The situation has now changed: ore grade is falling rapidly and is projected to be only 1.55% by 2003. Since revenue is directly proportional to ore grade, while costs are proportional to quantity of ore processed, profits will begin to fall dramatically. The Phase IV Expansion Project is intended to forestall this drop in profits by increasing ore processing capacity by over 85%.The Phase IV concentrator is designed for a nominal capacity of 110,000 MTPD and the key to achieving this value is through the proper design of the grinding circuit. This paper presents the general design criteria for the grinding circuit, as well as a description of the facility.INTRODUCTIONThe Phase IV Expansion Project consists of a new copper concentrator located 8.5 km south of the existing operations, a new tailings disposal and water reclaim system, a new concentrate slurry pipeline to the coast, and added concentrate handling capacity at the port of Coloso. The new concentrator has a nominal capacity of 110,000 tonnes per day (MTPD), compared to the existing concentrator’s capacity of 127,500 MTPD. The Laguna Seca concentrator is based on using the largest and most efficient ore grinding mills now available.The concentrator has been designed for a 110,000 MTPD nominal capacity. The process design criteria for the Phase IV project were established from in-house operating information and from test work. Unlike a green field project, Escondida already had an operating plant and it processes ore from the same pit that feeds the Phase IV plant. It is expected that the current mineralization will be similar for the first 6 years of operation of the new project. Therefore, some of the current plant operating conditions were incorporated directly into the design criteria."

Jan 1, 2004

By Paul J. Lewis

Estimation of the axial side shear resistance of drilled shaft rock sockets is directly related to the unconfined compressive strength of the bedrock. Commonly, the mean unconfined compressive strength value is calculated from a range of laboratory test results and is used to estimate the side shear of the bedrock. This paper presents the results from a full scale axial load test performed on an 8.5-feet-diameter drilled shaft rock socket, and compares measured side shear values to estimated values for two different rock strata. Measured side shear values correlated well with the design value calculated for the "strong" rock stratum, but did not correlate well with the design value calculated for the "weak" rock stratum. The mean unconfined compressive strength was used to calculate the side shear in both strata, but review of the laboratory data indicates that this value may not have been appropriate for the weak stratum due to a large variation in the laboratory test results. Also included in this paper is a discussion of the subsurface conditions, the laboratory test results, and the methodology used to design the drilled shaft rock sockets for axial and lateral resistance.

Jan 1, 2005

By D. E. Pollock, Andrew B. Cecala

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/nonmetal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 pct throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurization systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a worker’s clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

By H. Lyn Bourne

This is the ninth annual tabulation of royalty information. Again this year, some of the older information has been deleted to make room for more than 30 new entries. Several articles and publications crossed the author's desk this past year that relate to mineral valuation and mineral royalty. Tom Loucks presented a paper, "The Valuation of Hard Rock Mineral Property," at the Rocky Mountain Mineral Law Foundation in Santa Fe, NM in July, 1990. His paper gives an indepth explanation of the definitions and concepts related to mineral valuation. It includes descriptions of numerous legal cases that have dealt with mineral valuation and proper reference is given for each case. Loucks works for the Denver Mining Finance Co. Gold royalties generally range from 5% to 7%, net smelter return. However, Severn Brown sent information that shows a much wider variation. Echo Bay Mines reported in its 1989 annual report royalties that range from 1.5 % to 30% for gold from various gold properties. Brown also sent a copy of an article that appeared in the Dec. 27, 1982, issue of Fortune magazine. This issue carried an article by Walter Guzzardi, Jr. "The Huge Find in Roy Ash's Backyard." The article gives the history of Newmont's leasing in Nevada on property that became the Carlin, Bootstrap and Blue Star Mines. The article states that the initial royalty was 10% that escalated to more than 16%. Another property, the site of Gold Quarry, provides an 18% royalty to the same own¬ers. The article makes interesting reading for those interested in mining history.

Jan 1, 1991

By Eder Salazar

Como parte del desarrollo de sus operaciones de mina de cobre subterránea, la Sociedad Minera El Brocal S.A., desarrolló el método de minado tajeo por subniveles con pilares recorridas con el fin de incrementar su producción actual. En ese sentido, el presente texto señala la implementación de un método de minado conforme a las características geomecánicas del macizo rocoso del yacimiento.

Sep 12, 2011

The upper amphibolite-grade mctasediments of thc rinaroo area, North Queensland, form part of a regional aurcole to the large Tinaroo Batholith and are the stratigraphic equivalents of the Hodgkinson Formation of gencrally low metamorphic grade. There is no evidence of any lithological unconformity.The higher grade metasediments have a more complex deformation history than is typical for thc surrounding region and this may bc due to one or a combination of two factors; an additional strain componcnt associated wilh the intrusion of Ihe Tinaroo Batholith, or a more marked finite strain response to the overall regional stress field within hotter. more ductile rocks.Four deformational events can be characterized within Ihc Tinaroo Area. Close to Ihe Tinaroo Batholith D1 and D2, arc so strongly developed that they disrupl the continuily of Ihe original Iithological layering. In the aureole region, D1 is strongly overprinted and its original fabric intensity is obscured, but both D2 and D3 display a mappable decrease in intensity away from the granite margin. These three deformations occurred during Carboniferous or early Permian time. D4 is later and only patchily developed.The broad, moderate pressure metamorphic aureole surrounding the Tinaroo Batholith is a typical of the CairnsCooktown group of Permo-Carboniferous granitoids. which usually develop narrow, lower pressure contact aureoles. Two periods of metamorphism are distinguishable. The first reached peak temperatures somewhat greater than 520°C, the second temperatures around 620-630° C immediately adjacent to the granite contact.Several cale-silicate lenses containing scattered scheelite mineralization occur within the area. Scheelite appears to have crystallized at the same time as the cale-silicate minerals, its appearance coinciding with the intrusion of the Tinaroo Batholith. Unlike many "skarn-type" scheelite deposits, the scheelite-bearing cale-silicates are Fe-poor, with no positive correlation between total Fe and W.

Jan 1, 1982

Cobalt mostly occurs as a minor, but valuable, constituent in most nickel and a few copper ores, however it is not generally found alone in commercially viable deposits. Its concentration and extraction are therefore intimately linked to the recovery of the primary metals and the major task for the metallurgist is to extract cobalt of commercial grade from a much larger mass of either nickel or copper and sometimes both. With a particular focus on Vale Inco?s operations, this paper provides a brief overview of the mineralogy of the main deposits being currently exploited that contain cobalt as a co or by-product. The concentration and then extraction to metal are reviewed and some advances released into the public domain are discussed.

May 1, 2009

By J. Krzyzanowska

Paper written on project work carried out in partial fulfilment of Bachelor of Engineering-Mining Venetia Mine, an open-pit diamond mining operation in the Limpopo Province of South Africa, currently has a mixed haul truck fleet consisting of Caterpillar 785B and C; 789C; modified 793D and 793D. Even in an ideal situation these trucks have different cycle times, which causes queuing at the loading area and their different speeds cause bunching on the ramps, leading to higher overall cycle times and lower productivity. This problem was identified but the root causes of the problem were not investigated and quantified. A time and motion study on the haul trucks was thus undertaken to measure actual cycle times and compare them to ideal cycle times as well as to observe any reasons for deviations. Ideal cycle times are partly evaluated on the basis of simulation and partly from production optimization expert input. Several areas that affect production were identified and these include: haul road conditions, the control room, dispatching programme and dispatching data management, as well as truck-shovel matching. The investigation was important in establishing control parameters for haul fleet operation since time spent queuing is production time lost, which defers waste tonnes to later in the life of mine, thus decreasing the tempo at which kimberlite is exposed.

Jan 1, 2007

Past arguments advocating reverse circulation sampling against blasthole sampling are reviewed to present the debate under a different light. The advantages and disadvantages of each drilling method are compared, and the choice is presented as an informed trade-off between them.

Mar 1, 2010

Simulation and Analysis of Media Behaviour in the Tower Mill by Discrete Element Method for Estimating the Power Draw and Spatial Distribution of Grinding Process The trends to the Tower Mill (TM) for grinding the materials are increased recently due to its unique merits. Among the various considerations of this machine, the main important items are increasing the efficiency of grinding as more as possible while keep the power consumption, manufacturing and maintenance costs as less as possible. Because this grinding process includes a huge numbers of media particles (ball or other shapes) that are interacted with each other and body of the machine, the DEM (Discrete Element Method) way is a very useful and essential step to getting confident evaluations. Because the DEM simulation is a very young scientific field and proper commercial software are very rare and still under modification, at first step, a FORTRAN code is developed for DEM simulation of two laboratory Tower Mill models (KM5 and KD5). The simulation and experimental results matched each other properly. Then one another DEM software was implemented to perform simulation of bigger models (huge numbers of balls), meanwhile could handle the complex 3D geometry data. The simulation and experimental results were compared and analysed in detail for not only laboratory but also for industrial models (KW5, KWD5, KWD50, KW300F, KW700F and KW1500) without any manipulation or compromising of the parameters of simulation. Some numeric data of industrial models are hidden here due to confidential reasons. The relative velocity of balls (ball-ball and ball-TM body), dissipate energy, interacted forces and stresses during the process are the key outputs of DEM simulation for design this machine. Therefore the main important processes in a Tower Mill machine are recognised and consequently some horizons of development of this machine are distinguished.

Sep 13, 2010

By F T. Suorineni, L Baird, A Papaioanou, D Hines

The Mathews et al (1981) stability graph was developed to provide guidance in the determination of stope sizes to control dilution in bulk mining of large orebodies. Longhole and sublevel open stoping (LHOS and SLOS) are the lower end in scale of underground mass mining with panel and block caving (PBC) at the higher end. Currently, the stability states of stopes in the stability graph are described qualitatively as stable, unstable or cave. The alternative quantitative option to the qualitative stability graph is the Equivalent Linear Overbreak Slough (ELOS) stability graph. The ELOS stability graph only applies to narrow vein orebodies. It is easy for the Mathews et al (1981) and the ELOS stability graphs to be applied outside the limits of their databases. What is currently referred to as ‘stable’ in the present stability graphs has diverse interpretations at different mines depending on their acceptable dilution values. In 2014, a research program was conceptually conceived at the UNSW Australia School of Mining Engineering to develop a quantitative dilution-based stability graph independent of orebody width to address some industry concerns on the use of the stability graphs. A dilution-based stability graph provides the mining engineer the flexibility to determine open stope sizes based on what dilution amounts are acceptable. The graph also unifies both the Mathews et al (1981) and ELOS stability graphs for wide and narrow vein orebodies, thus, eliminating their potential misapplications. To date, the concept is proven with case studies from metalliferous underground mining operations located across Australia. This paper presents the dilution-based stability graph concept, the initial results and future plans to account for other critical factors and increase confidence in its application with the addition of more data outside Australia.CITATION:Suorineni, F T, Papaioanou, A, Baird, L and Hines, D, 2016. A dilution-based stability graph for open stope design, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 511–522 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Cuppam Dasarathy

The incidence of liquid inzmiscibility in binar)) indium alloys has been theoretically analyzed on the basis of the Hildebrand-Alott equation. Bedictions of miscibility or otherwise Imve in general been found to agree with those phase diagrams that are already publislzed in the literature. Out of a total of 27 systems, where either the complete phase diagrams are published or liquid immiscible behavior is reported, the Predictions agree with the experimental data in 25 systems, the exceptions being the Te-In and Ni-In systems. According to the equation, liquid immiscibility is also indicated in the binary alloys of indium with K, Rb, Cs, Na, Sr, Ba, Ti, Zr, V. Nb(Cb), Ta, W, U, Re, Ru, Rh, Os, and Ir. RECENT investigations by the author have shown that indium when alloyed with iron, chromium, and cobalt shows liquid immiscible behavior.1"3 The Fe-In phase diagram shows a wide range of compositions where the liquids are immiscible.4,5 No intermediate phases are present in this system. No precise information is available about the extent of liquid immiscibility in the Co-In system. However, it is certain that there is a range of compositions where the liquids are immiscible and that there are two or three intermediate phases,376 in the system. Liquid immiscibility is also strongly indicated in the Cr-In system and no evidence was obtained in the brief investigation to indicate the presence of intermediate Cr-In phases.2 The present paper deals with a theoretical analysis of binary alloys of indium with certain elements of the periodic table and indicates the systems where liquid immiscibility may be expected. The incidence of liquid immiscibility in binary systems has been theoretically examined by many workers and many excellent papers are available on the subject. In this paper, the alloy systems are examined on the basis of the more recent ideas proposed by Mott.7,8 It has been claimed8 that the Mott parameter predicts the incidence of miscibility or otherwise with reasonable accuracy and consistency. BACKGROUND TO MOTT&apos;S APPROACH Hildebrand applied his immiscibility rule for non-polar liquids to various alloy systems.9 The basis of this rule is that the equation for the excess free energy of formation of a liquid solution is rather similar to the theoretical expression for the energy of mixing of a regular solution. He postulated that when the heat of mixing is sufficiently high, separation into liquid phases will occur and the condition for complete CUPPAM DASARATHY is at the Research Centre, British Steel Corporation, (South Wales Group), Port Talbot, Glamorgan, Great Britain. Manuscript submitted March 12, 1969. IMD miscibility was shown as where VA and VB were the atomic volumes of the components A and B, and ?EV the energy of vaporization of the component. The term (?EVA/VA)1/2 was regarded as a measure of the binding energy of the component A and was called the L&apos;solubility parameter" 8A. On this basis immiscibility occurs when 1/2(VA+VB)(bA-bBf > 2RT [2] Apparently, however, there were several inconsistencies in that according to Eq. [2] several systems known to be miscible in the liquid state were predicted as immiscible. MOTT&apos;S ANALYSIS ~ott&apos;" regards that the reason for the inconsistencies arising out of Hildebrand&apos;s equation was largely due to the electrochemical attraction between the two elements, not being considered. Hence, Eqs. [I] and [2] were modified by taking into account the electro-negativities of the two elements XA and XB, and Mott arrived at an equation for immiscibility, i(VA + VB)(6A - aB)2 - 23,Q60n(XA - XBf > 2RT [3j which can be written as i **&£*&* >&apos;*°™- &apos;• HI T being the melting point of the more refractory component of the system. In Eq. [4], the numerator was called the Hildebrand term, the denominator, the electronegativity term, and their ratio, the Mott number. Mott observed that if the Mott number of a given binary system was greater than the maximum number of Pauling bonds which the two metals could form, then liquid immiscibility could be expected. The maximum number of bonds formed by a given metal was considered to be directly related to the number of bonding electrons available, i.e., to its maximum valency. Since the valencies of the elements considered vary from 1 to 6, Mott assumed that if the ratio of the Hildebrand term to the electronegativity term was >6, then immiscibility could be expected. On the contrary, if the ratio is <1, the metals should be miscible. Further, the alloying behavior is not only influenced by the valencies of the two elements but also by the relative atomic sizes that influence the types of packing and hence the coordination number. Mott considers that on average the maximum number of near neighbors of unlike atoms is 6. Thus, on both valency and size factor considerations, Mott concludes that the maximum number of bonds&apos; possible in any system was 6, this being the upper limit of the Mott number for miscibility. In considering the alloying behavior of systems with Mott numbers between 1 and 6, Mott plotted the num-

Jan 1, 1970

By N T. Moxon, L W. Armstrong

Explosive manufacturers have for many years provided a service to the mining industry which has,until recently, been unchallenged by mine operators. Today mine operators are more aware of the properties of explosives required to perform particular tasks within their operations. These properties can be reliably quantified using the test procedures described in this paper for emulsion adn ANFO based explosives. Details of an end-user sampling programme desgined to provide quality checks on explosives supplied to a mine site are also discussed.

Jan 1, 1991

By Philip Bonanno

The first major project in Boston&apos;s new access to Logan Airport was an Immersed Tube Tunnel which extended 3,600 ft. from South Boston to East Boston across Boston Harbor. Twelve tube sections, 300 ft. long x 80 ft. wide x 40 ft. high, were lowered into an excavated trench which was then backfilled. The depth of the trench at mid-channel was approximately 100 ft. below mean high tide. At the East Boston end the tube terminated close to the present shoreline. At the South Boston end the tube terminated approximately 600 ft. inland from the shore line where a ventilation building was required. The depth to subgrade from existing ground at the ventilation structure was approximately 85 ft. The soil profile at this location consisted of 50 ft. of miscellaneous rubble fill, 25 ft. of Boston blue clay, and 10 ft. of glacial till. A small amount of weathered argellite existed at the north end of the structure. Part of the Morrison Knudsen, Interbeton, J.F. White, Joint Venture contract to construct the Immersed Tube Tunnel (ITT) was the construction of a cofferdam at the tube/ventilation building interface. The ventilation building was to be built as part of another contract. The construction of the cofferdam and the excavation to the building subgrade was the responsibility of J.F. White Contracting Company.

Jan 1, 1994

By C. E. Wood

Because of the renewed importance of the strategic metal manganese the Bureau of Mines in conducting further research on pyrometallurgical methods of beneficiating manganiferous iron ores and low-grade manganese ores. Published data on the Pyrometallurgical of manganese ores have been reviewed by Joseph.5/ A method of treatment that has received less consideration than others is the matte smelting of manganese or the separation of manganese from the iron and the gangue in an ore b, formation of a matte, that consists principally of esulfide of manganese. A procedure of this type has been patented by Betts.6/ Lofquist7/ claims advantages for the production of a sulfide-oxide matte as a method of recovering manganese in alloys containing manganese and iron.

Jan 1, 1940

By Steven K. Ruggieri

This report describes the use of the sprayfan auxiliary ventilation system for methane and dust control on continuous miner sections to potential users. The sprayfan auxiliary ventilation system is a modified water spray system which directs intake air to and across the front of a continuous miner to prevent build up of methane gas and dust concentrations. This user&apos;s manual contains practical information concerning sprayfan: a. Description and capabilities b. Design c. Installation d. Operation e. Maintenance. Underground tests, independent laboratory tests, tests by MSHA, and independent installations by coal producers have confirmed the performance of the sprayfan system. There are currently 150 sprayfan systems in operation in underground coal mines.

Jan 1, 1981

By Michel Ruel

"PID loops – also known as base layers or regulatory controls – form the foundation of any plant’s control layer and it is generally accepted that PID loop health has a direct impact on the plant’s bottom line. Keeping these thousands of control loops in good health has a direct impact on the plant’s bottom line: it reduces variability, improves quality and throughput, and decreases energy costs and raw material usage. This has been well proven and documented in many articles. In the last ten years, technology has evolved: control engineers can now keep track of control loop performance and link it to the root causes of variability. However, they lack industry-wide best practices and criteria for determining what can be considered as excellent, good, fair, or poor performance. To ensure that PID control loops continue to perform well and meet their objectives, control engineers need a combination of (a) an appropriate monitoring technology and (b) best practices for doing the maintenance of base layer controls.Most plants have limited resources and operate with an increasing number of constraints; therefore, using the right tools and including reports in daily workflow is key for success. This paper suggests roles and responsibilities of key players needed to work toward control performance best practices and discuss organisational changes to succeed.INTRODUCTIONAlthough PID controllers are reliable workhorses in the process industry, they are often underrated. Since the 1980’s, computer control has evolved and the control algorithms used by control engineers have become increasingly complex. However, PID controllers still handle over 90% of the control loops in operating plants. Table 1 shows the savings that can be realized by achieving best-practice in several different process control categories (Brisk, 2004). The savings are expressed as a percentage of production costs."

Jan 1, 2011

By Liqun Liang

Various nondestructive testing (NDT) inspection methods are available to evaluate the structural integrity of cast-in-place shafts. The widely used methods include Cross Hole Sonic Logging Testing and Low Strain Testing. Due to its advantages such as low cost, easy operation, quickness and flexibility (no need to plan ahead and prepare inspection tubes or other devices), Low Strain Test is frequently specified in quality assurance programs of many countries or when doubts arise as to the integrity of the finished shafts/piles. The method is well suited for small to middle sized shafts. However it is an indirect NDT testing method and has certain limitations. Data interpretation requires proper training, experience and judgment and, therefore, inconsistent conclusions and reporting may be provided by different testers. To avoid or reduce such inconsistencies, it is best to follow a standardized data interpretation and record classification system. In this paper, a new classification method is presented with examples. A step-by-step data evaluation and interpretation procedure is proposed with examples of real cases to help understand the LST data. The paper also makes recommendations for measures to be taken when anomalies are detected in tested production piles.

Jan 1, 2011