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By Shoichi Tsukuni, Akihiko Uchida, Kazuo Konishi

"In order to investigate the effect of grid-form deep mixing walls as a countermeasure for liquefaction damage to roads and private houses in Urayasu, Japan, three dynamic centrifuge model tests were conducted. Urayasu is located in the Tokyo Bay area, and private houses in the city incurred severe damage due to liquefaction during the 2011 Tohoku earthquake. In grid-form deep mixing walls design, the distance between grid-form walls is critical to prevent liquefaction. This study clarifies the relationship between the settlement of private houses and the distance between grid-form walls under the conditions that exist in Urayasu.INTRODUCTIONMany private houses in Urayasu, Japan suffered severe damages due to liquefaction during the 2011 Tohoku earthquake (Photograph 1). Fig. 1 shows the location of Urayasu and the maximum acceleration of the observed seismic waves in the Tokyo Bay area. At Urayasu, the duration of the seismic waves (hereafter called the Urayasu Wave) was about 2 min. The maximum acceleration was 1.57 m/s2 (Fig. 2), which is relatively small. The damages occurred in the land reclamation areas that consist of loose sand with an SPT-N value less than 10.To prevent liquefaction in future, it is necessary to adopt suitable countermeasures in the areas where many private houses suffered severe damages. Grid-form deep mixing walls are one such countermeasure. Fig. 3 and Photograph 2 show grid-form deep mixing walls. Walls are constructed using the deep cement mixing method. Fig. 4 shows a plane view of planned grid-form deep mixing walls for roads and existing private houses in Urayasu."

Jan 1, 2015

By I. Loomis, D. Rachmad, I. Duckworth

During the past two years the Underground Mine Ventilation Group at PT Freeport Indonesia has undertaken to upgrade their Hygiene Laboratory. This process has included upgrading equipment for dust sampling and gas monitoring, as well as procurement of an OCEC analyzer for Diesel Particulate Matter analysis. While the laboratory equipment represents one factor, these changes have also required re-evaluation of the sampling protocols and the burden of ventilation monitoring personnel. This paper provides a review of these experiences.

Jan 1, 2006

By B. Benmokrane, G. Ballivy

"RésuméLe mécanisme de transfert des charges et le processus de décohésion le long des scellements d'ancrages scelles dans des massifs rocheux sous des charges de tensionnement peut être examine par instrumentation de l'ancrage à l'aide de jauges de déformation. Dans ce contexte il est présente ici les résultats d'une étude, en vraie grandeur sur chantier, ayant porte, d'une part sur des essais d'arrachement conventionnels et d'autre part sur des essais déflagrée barres d'ancrages instrumentées et scellées à l'aide d'un coulis de ciment dans un massif rocheux sain et compètent. Les résultats décrits ici, particulièrement les profits de contraintes de cisaillement le long de l'ancrage, obtenus à partir des valeurs de déformations relevées sur les jauges, ont permis de préciser le niveau de chargement correspondant à la décohésion initiale du coulis de scellement, d 'examiner l'effet de la décohésion sur la distribution des contraintes et de caractériser le fluage du système barre d'ancrage/coulis de scellement.ABSTRACTThe load transfer mechanism and the debonding process along grouted rock anchor, subjected to tention loads, can be examined through the instrumentation of the anchor with the aid of strain gauges. In this context, the resultsof a full-scale site investigation including classical pull out tests and creep tests are presented in this paper. These tests were performed on instrumented bars which were cement grouted in a competent rock mass. Results presented in this paper concern, among others, shear stress pro/ties along the grouted anchors which were determined from strain values obtained from the strain gauges. These results have been used to: (1) predict the load level corresponding to initial debonding of the grout; (2) study the effect of debonding on shearstress distribution along the anchor; and (3) characterize the creep behavior of the bar anchor/cement grout system."

Jan 1, 1991

By Pierre Lacoste-Bouchet, Ian Orford, Mike Cooper

"The Brunswick Mine ore requires fine grinding to achieve liberation of minerals. With 25mm slugs as the grinding media in the ball mill, there was a limitation of a P80 of 25 microns on the CuPb regrind circuit. Results from pilot plant testing showed that the separation efficiency could be increased through fine grinding with a P80 of 15 microns.Options considered were the capital expenditure for new fine grinding equipment such as a vertimill or the use of the present ball mill equipment with smaller media. The Wheelabrator Allevard Enterprise (WAE) millpebs product was chosen because it was a smaller media with a distribution of steel pellets between 5 to 12 mm.With millpebs the grinding product was reduced in size from a P80 of 25 microns to a P80 of less than 19 microns. The power draw to achieve the finer grind was 13% lower while the media consumption was 57% higher.The millpebs grinding media was also tested on the zinc regrind mill. The purpose of the trial was to understand what the media consumption and power draw would be with the charge lowered to achieve an equivalent grind as obtained with the slugs. The media consumption was approximately the same and the power draw was reduced by 30%.INTRODUCTIONThe Brunswick Mine ore is a complex Pb-Zn-Cu-Ag sulphide ore with the grain size of the minerals varying from submicron blebs to particles up to several mm in size. The ore is ground progressively finer in stages. The first step of grinding occurs in the SAG mill circuit. The product sizing 80% passing 95 microns is fed to the CuPb prefloat stage (Cormier et al 2002). The tails from the prefloat is then further ground to a P80 of 35 microns for the CuPb rougher flotation. The final liberation for the CuPb circuit takes place in the CuPb regrind circuit. The regrinding mill further liberates the cleaner scavenger concentrate, second cleaner tails and third cleaner tails. The reasoning for the progressive grinding is to achieve fine grinding without having galena over ground due to its high specific gravity that preferentially sends it to the cyclone underflow."

Jan 1, 2006

By E. P. Barret

Differences in the reducibility of iron oxide materials have been recognized for a long time. Limonites are deoxidized more readily than hematites, and unaltered magnetites are the most difficult to deoxidize. Sinters are found between hematites and magnetites and vary considerably in reducibility, depending on the sintering practice followed and on the degree of fusion of the product. The increased activity in the beneficiation of taconite recently has made available a new blast-furnace raw material, namely, iron oxide pellets made from magnetic taconite concentrate. Many of the data in this paper apply to these pellets, or glomerules, as they were called when this method of agglomerating iron ores was first considered. To clarify the terms applied to iron oxide materials in this paper, the following definitions are given. Agglomeration is the general term applied to all methods of compacting or consolidating fine iron oxide materials. Sinter is the product from a Dwight-Lloyd or Greenawalt sintering machine. Pellets are formed by balling fine, moist oxide in a rotating drum at room temperature, followed by heating in a shaft furnace to a temperature below that of incipient fusion to develop a permanent bond. Nodules are formed by heating the iron oxide material to incipient fusion in a rotary kiln. Briquets are formed in a mold under pressure, with or without the addition of a binder, and burned to develop a permanent bond.

Jan 1, 1949

By C. O. Lee, Z. W. Bartlett, R. H. Feierabend

The Grand Isle sulfur mine is located in the Gulf of Mexico, approximately seven miles off the coast of Grand Isle, Jefferson Parish, La. The deposit is on acreage covered by oil, gas, and mineral leases originally issued in favor of Humble Oil & Refining Co. by the State of Louisiana which were continued, maintained, and redesignated by the U.S. Department of the Interior after passage of the Outer Continental Shelf Lands Act. The sulfur deposit was discovered in 1949 when Humble Oil & Refining Co. penetrated more than 200 ft of sulfur-bearing limestone in a zone between 1813 and 2075 ft below sea level. In 1954, Humble drilled ten more sulfur prospect holes, eight of which encountered sulfur ore. On September 19, 1956, Freeport Sulphur Co. acquired from Humble Oil & Refining Co, the sulfur rights underlying the tracts, and the actual design of the installation began the same month. The first structural contract was awarded in December 1957 and offshore erection began in June 1958. The initial phase of construction has been completed and production by the Frasch process commenced in April 1960. The estimated total cost of the project is $30 million, of which $8 million is the extra cost incurred by the necessity of offshore operations. More than $22 million was expended before production was started. GEOLOGY OF DEPOSIT Grand Isle is the third largest sulfur deposit in the U.S. The orebody embraces several hundred acres, but its outer limits are yet to be defined to the northeast, east, and south. Most Gulf Coast sulfur deposits occur in a caprock mantle of calcite (referred to as limestone), anhydrite, and occasionally gypsum, which covers the apex of an intrusive mass of salt. Commercial quantities of sulfur are usually confined to the calcite or limestone member. Most often such limestone is completely enclosed by dense anhydrite below and impervious sediments above, which effectively form a closed reservoir. The depth of the Grand Isle orebody ranges from 1800 ft to 2500 ft below sea level. Within the present boundary, the sulfur-bearing limestone varies in thickness from 220 ft to 425 ft, while the sulfur content varies an average of about 15 pct in the leanest hole to an average of about 30 pct in the richest. Rock containing less than 5 pct sulfur is not classed as ore, and holes assaying less than 20,-000 long tons per acre of sulfur in place are not considered commercial offshore. The sulfur enrich-

Jan 1, 1961

By H. R. Shell

Fluorphlogopite mica was synthesized from inexpensive and abundant olivine, clay, feldspar, and sand (plus K2SiF6). The raw materials were melted in crucibles and in an internal resistance electric furnace. The melts yielded >95 percent mica. The major difficulty encountered was incomplete settling of the highly dispersed ferroalloy. This problem was not completely solved. Reducing agents tried in melts of 300 to 400 pounds were carbon, silicon, and silicon carbide. Carbon slowly reduced the iron of the raw materials, with much fuming. Silicon apparently was oxidized ahead of the melting and was ineffective under the conditions obtained. By far the best reducing agent was silicon carbide. With silicon carbide, fuming did not occur and ionic iron content of the mica flake approached 0 percent. However, even with SiC, the highly dispersed globular iron did not completely separate from the mica portion. The fluorphlogopite made during this investigation should be suitable for metallurgical use. A byproduct ferroalloy containing about 5 percent nickel, 3 to 5 percent chromium, and some cobalt was obtained. Because of the highly dispersed metallic ferroalloy, the mica was not deemed suitable for electrical or electronic uses.

Jan 1, 1962

By D. Mohan

Soft to medium dense silty and clayey soils are found in many parts of India and conventional friction piles have normally been used for foundations of high rise buildings and other structures on such soils. The author investigated the use of Bored Compaction Piles and these have been used on these soils achieving substantial economies in cost over conventional friction piles. Similarly highly expansive clays, commonly known as Indian Black Cotton Soils occupy about 20 percent of the Indian land area. Short bored underreamed piles have been developed for such soils and a very large construction of various types of buildings and other structures have come up on such piles over the last thirty years in various parts of the country. The paper describes investigations leading to the design and development of both these type of foundations.

Jan 1, 1989

By F. F. Netzeband

This report relates to the sulfur industry of seven States--Arkansas, Kansas, Louisiana, Mississippi, Missouri, Oklahoma, and Texas--and is part of a national study of the sulfur industry by the Bureau of Mines. Markets as used in this report are divided into two components for individual analysis-- (1) supplier markets which include regional Frasch and byproduct sulfur producers and (2) consumer markets which include processors and manufacturers requiring sulfur in their operations The term sulfur as used in this report includes brimstone, native sulfur, elemental sulfur, or sulfur equivalents.

Jan 1, 1964

The reality of rising electrical power costs and the haunting prospect of decreasing electrical power availability are a threat to the growth of new projects and expansion programmes that could negatively affect the sustainability of mining operations. These threats require the adoption of effective power saving measures aimed at three principal objectives: the elimination of wastage, the reduction of power usage particularly during peak demand periods and, more importantly, improving the efficiency of high power-demand processes. It is reasonable to assume that the greatest impact will be achieved by concentrating on those processes that are large electrical power consumers. For Anglo Platinum operations, mine ventilation and, currently to a lesser extent, mine cooling are two continuous processes that fall in this category. It is estimated that these may consume fifteen to thirty-five per cent of the power delivered to the shaft head-depending on the shaft's design. Mine ventilation systems suffer from inherent, historical inefficiencies that lead to excessive power consumption. Air cooling systems are designed to be energy-wise in terms of modulating refrigeration plant operation to meet the underground requirements while maximizing use of 'free' cooling from surface conditions. Currently about ninety-five per cent of the refrigeration capacity used in Anglo Platinum mines is dedicated to surface bulk air coolers. The net thermal efficiency of these systems is compromised as mines expand in depth and on strike. Looking to the future, this practice will be complemented by more energy demanding underground cooling tactics requiring considerably higher electrical power consumption per unit ton produced. To counter this increase in power consumption, more energy-efficient systems and advantageous transient strategies such as thermal storage and the use of ice-on surface and possibly even underground-are being considered. This paper describes work currently undertaken and planned by Anglo Platinum operations to reduce power consumption by main fans during off-shift periods, the associated efforts currently introduced to reduce underground air leakage, the possibility of introducing more efficient auxiliary ventilation systems, the feasibility of thermal storage, and a brief look at energy recovery system as a means of countering the anticipated power demand associated with underground cooling. Keywords Mine ventilation, mine air cooling, energy efficiency, chilled service water, energy recovery, air wastage, fan selection.

Jan 1, 2011

By D. B. Rebuli

Seismic networks in deep gold mines of South Africa are often planar owing to the tabular geometry of the orebody and, therefore, the mining infrastructure. Consequently, seismic event locations are poorly constrained in the direction perpendicular to the reef plane, and symmetrical locations above and below the reef plane may fit the observed data equally well. This problem may be resolved in situations where the strata above and below the reef plane have significantly different seismic velocities, which is the case for the Ventersdorp Contact Reef at Kusasalethu mine (previously Elandskraal, the amalgamation of Deelkraal and Elandsrand). A location method using a layered location model that takes into account the velocity contrast between the layers was tested. Observed direct- and head-waves were used to determine the velocity bounds of the P-wave velocities in the two-layer model. The data-set was also used to find the best P- and S-wave velocities for the two layers by grid searching over a range of velocities and minimizing the sum of the travel-time residuals. The results from the grid search and those from the calibration of velocities using direct- and head-waves give similar P-wave velocities for each of the two layers. A second set of seismic events was then relocated with this layered model and locations closer to reef were found. This simple layered location method goes some way to reduce the reefperpendicular location errors for Kusasalethu mine in particular. Keywords mine seismology, velocity model, location methods.

Jun 1, 2013

By L. Vollert

In August 2018, the first full-scale HydroFloatTM cells for the recovery of coarse composited copper and gold were commissioned at Newcrest’s Cadia Valley operation in New South Wales, Australia. The primary objective of the installation is to recover coarse value-bearing composites that are lost to conventional flotation tailings, without the need for additional power input for particle size reduction to improve mineral liberation. This paper examines the application of Eriez HydroFloatTM technology for the recovery of coarse, poorly liberated copper sulphide particles drawing on recent experience from lab scale testwork through circuit design and commissioning of the full-scale installation at Cadia Valley. INTRODUCTION In the face of declining copper head grades and a tightening regulatory environment around the use of wet tailings dams, the processing of copper ores at coarser particle sizes has become a focal point for the industry. Sulphide flotation using the Eriez HydroFloatTM is one of the emergent technologies that sits under this umbrella of coarse pre-concentration. It has been demonstrated through numerous lab and pilot scale testwork programs carried out by Newcrest and others (Awatey, Kohmuench, Thanasekaran, Skinner & Zanin, 2013), to improve the flotation recovery of sulphide-rock composite particles with low surface liberation, relative to conventional flotation technology. The HydroFloatTM technology has been used widely for the recovery of coarse potash, phosphate, coal, vermiculite, spodumene and diamonds but has never been applied at full scale in either gold or sulphide flotation. In August 2018, the first full-scale 3.4 m diameter HydroFloatTM cells for the recovery of coarse composite copper and gold were commissioned at Newcrest’s Cadia Valley operation in New South Wales. The primary objective of the installation is to recover coarse value-bearing composite particles that are lost to conventional flotation tailings, without the need for additional upfront power input for particle size reduction to improve mineral liberation.

Jan 1, 2019

The use of walk-through inspections, approvals and ad hoc investigations to ensure risk is kept within acceptable levels is reaching its limits of effectiveness. Further improvement in occupational health and safety requires a systems approach, and the use of Quality Management principles is an obvious basis for this. SafeGuard, a æbest practiceÆ model health and safety management system and audit criteria based on AS/NZS ISO 9001:1994, has been produced by the Department of Mines and Energy. Quality style audits of mine and quarry health and safety systems are now being carried out by the Inspectorate.

Jan 1, 1998

By R. Stefanko

This Final Report covers the work performed for Contract No. H0377043, "Cables for Face Equipment" from August 1, 1977 to April 1, 1981. It reports the findings in three areas of research: cable protection, circuit-breakers, and high-voltage cable couplers. Laboratory and analytical studies have been conducted in the three areas to determine proper circuit-breaker settings, cable sizes, and coupler performance. Also, an extensive field-monitoring program was established to relate in-mine epxerience to laboratory findings. Further, various pieces of equipment was designed for laboratory testing, particularly in the area of cable reeling and unreeling.

Jan 1, 1981

By Stephen C. Tadolini, Thomas M. Barczak

A critical safety component for all underground mining is intrinsic and standing support systems. Specifically, tabular hardrock mining exploits a wide variety of deposits that require various methodologies to safely mine the ore material. Several new support systems have been developed in recent years for hard rock applications which have been modified or applied in a variety of ground control applications. These include prestressing devices, improved cribs, and free standing supports. Various standing support and prop-type systems have been designed for hardrock applications with seismic loading conditions to accept prestressing. The prestressing, using water-filled cells, creates an active load upon installation and is considered essential to maintain support during and after the blasting of the mine faces. Heavy seismic activity is also present in these mines and the prestressing units can provide some energy absorption capability to help preserve the integrity of the support. This paper presents an overview of these innovations in support technology.

By Pedro Lilienfeld

The objective of this program was the development, design, fabrication, and laboratory testing of a mine-worthy continuous respirable dust monitoring system (CRDMS). The operation of the sensor unit of this system is based on the light scattering intensity of the respirable fraction of airborne dust. The CRDMS is compatible with the typical environmental rigors that characterize coal mines and, in particular, the shock, vibration, impact, moisture and dust conditions prevailing at active training machines. The sampled area must be within the breathing zone of the mining machine's operator, whose dust exposure is to be monitored by the CRDMS sensor unit. Instantaneous, as well as shift-averaged dust concentrations, are displayed and recorded for later retrieval, Alarm indications and other diagnostic information are provided. The project was completed with the delivery of three sensor/display units (SDU), one data retrieval unit (DRU), two mining-machine-compatible power supplies, and two [auxilliary] battery packs.

Jan 1, 1983

Historically, the selection of mining sequence for multiple seam conditions has been based on many factors other than ground control considerations and minimization of interaction effects. Today, numerous operations are finding themselves mining above existing or abandoned operations, some of which exhibit large scale caving, pressure arches and subsidence troughs. Development of design criteria for the upper seam that would alleviate damage due to lower seam interaction effects can contribute substantially to the safety and productivity of many mining operations. The primary objective of this re search has been to identify methods of improving ground control conditions in the upper seam when mining through either passive or active subsidence waves. These methods concentrate on improved ground control practices for the upper seam, rather than reducing the amount of subsidence in the upper seams by improved practices in the lower seam. Design factors such as pillar size, pillar and opening orientation relative to the subsidence trough, offsetting intersections, and different support methods have been studied for the upper seam in a variety of typical geologic environments. Analysis has demonstrated criteria for ameliorating negative interaction effects and facillitating design in the superincumbent seam.

Jan 1, 1986

Future metal prices play a direct role in both the economic evaluation and short to medium planning of a mine scheduling sequence. It is difficult to predict with accuracy the future price of volatile metal commodities, however, it is possible to fix some future metal price, outside of long term contracts by the selling of futures contracts through a commodities exchange. The futures contract represents a fixed amount of a specified quality of a commodity for future delivery at a predetermined price. Several different types of hedging are possible, one in particular which is best suited for mining companies. There are relative advantages and disadvantages when trading in futures contracts and particular reference is made to gold contracts on the Sydney Futures Exchange.

Jan 1, 1980

By A. A. Berk

The Bureau of Mines devised a test nipple for the field study of corrosion in the condensate-return lines of Federal heating plants. Corrosion surveys, made with this device, showed that the deterioration of the piping was caused principally by carbonic acid in the steam condensate. Corrosion problems were brought under control when the carbonic acid concentration in the condensate was decreased. In many instances, this was effected by decreasing the total carbon dioxide content of the feedwater; in others, the condensate acidity was neutralized with volatile, alkaline chemicals. Filming treatment with octadecylamine, reported successful in controlling return-line corrosion in industry, was much less effective in Federal area-heating plants. Laboratory study by the Bureau disclosed that octadecylamine is unstable in heating systems. Analytical methods were developed for this chemical and its degradation products in heating-plant condensate. Field surveys, in using these methods, confirmed the instability of the filming material. Laboratory tests showed that the degradation products are not useful film formers. Since filming treatment has little effect on condensate corrosivity, the piping was corroded where it was not coated by the treatment chemical.

Jan 1, 1962

By Slawomir Bock

One of the fundamental issues having a great influence on the safety of operations performed in underground mines is the support of workings which should assure their stability in a given geological setting and mining-technical conditions during the life of their use. The process of designing and planning support for roadways may use analytical and empirical, as well as numerical methods. In view of the rapid increase in the data processing capacity of computers and the development of more and more enhanced software for numerical modeling, it seems to be advantageous to use numerical methods in searching for design solutions ? especially in the case of non-typical mining and geological conditions and in cases that need to take into consideration a great number of factors. The assessment of rock mass quality is of basic significance in designing mine supports. Fractures, dividing the rock mass into blocks, have an essential influence on the stability of the rock mass and underground construction. This paper presents examples of the fundamental underground investigations on the rock mass conducted by the Department of Extraction Technologies and Mining Supports of the Central Mining Institute in Poland, such as: penetrometric tests, introscopic examination, laboratory testing of rock samples and ground penetrating radar. Moreover, this contribution also presents examples of applications of three-dimensional numerical modeling for the purposes of stress-strain analysis of the rock mass around mine workings and computer-aided support design by means of FLAC3D (developed by Itasca) and Cosmos/M (developed by Structural Research and Analysis Corporation).

Jan 1, 2009