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By W. C. Lacy

This article is a progress report of a program designed to quantitatively evaluate geological parameters to predict stable slope angles. The author feels that, although there does not appear to be any one technique or characteristics that will suffice as an index to the determination of stable slope angles, a combination of seismic methods as outlined here, detailed geological mapping and logging of core, and a better understanding of the angle of internal friction in rock types will permit accurate estimation. A mining engineer friend once remarked, "If we don't have pit slope failures, the slopes are too flat." Since economic justification of an open pit project is based upon ultimate pit slopes, we cannot wait until the pit is developed and slopes established by trial and error. Some combination of geological and/or geophysical techniques must be developed to permit accurate prediction of stable slope angles and to suggest modification of pit outlines to result in slopes enabling maximum economic yield. This presentation is a progress report of a program designed to quantitatively evaluate geological parameters to predict stable slope angles. The principle of the weakest link applies to any slope stability evaluation and necessitates detailed geological examination and recording of observations. Physical failure will occur along any surface where shearing stress exceeds shearing resistance. Rock conditions are seldom uniform even within a single cut or pit face, so stability conditions will vary. Consequently, both plan outline and ultimate slope limits must be tailored to the specific situation. Economic advantages to be gained by slight increases in slope angles in deep pits are well recognized and stimulate efforts to obtain maximum permissible slope angles. MECHANICS OF SLOPE FAILURE Excellent reviews on the nature of slope failure have been presented+2,6,8,11 For the purpose of this study, the writer considers failure to take place by one or more of three processes: 1) ravelling, 2) translation or slope failure, and 3) rotation or base failure (Fig. 1). The effects of increased pore water pressure in soils were recognized in 1923 by Terzaghi in his development of the concept of effective stress, and he has applied the same principle to jointed rocks designating water pressure as cleft-water pressure.8 Cleft-water pressure in a rock slope reduces normal pressure on the plane of failure, thus reducing shearing resistance and resulting in slope failure. In the following discussion it is assumed that adequate drainage is supplied to prevent any build-up of water pressure. This is the first step in any program to establish maximum slopes. Ravelling: Ravelling occurs in rocks with low cohesion and entails the free movement of individual fragments ranging from single rock falls to running ground. Removal of lateral support wherever slope angle exceeds the angle of repose of the rock parti-

Jan 1, 1963

By Cory J. E. Yacyshyn

Anchored steel pipe piles are being used more frequently in British Columbia for shoreline projects such as public ferries, cruise ship docks, containership terminals and locally in the expansion of the Vancouver waterfront convention center. While a 36? diameter driven pile may provide adequate compression loads it will not always achieve enough penetration to provide the required tension loading. That is why bundles of threaded anchors or strands are drilled through the center, past the pile tip, and anchored into the underlying strata. Drilling up to 250 feet deep through the piles in variable water bearing strata presents challenges. Southwest Contacting Ltd. (SWC) recently completed the three largest anchored pile projects in BC; Vancouver Port and Convention Center Expansion, Vanterm Container Terminal and the new Prince Rupert Cruise Ship Terminal. This paper will present the separate challenges encountered drilling the anchors. At Prince Rupert, the recently completed Northland Cruise Ship Dock ultimately required a cased system to drill and install triple thread bar anchors. When 200 foot long steel pipe piling was unable to penetrate the highly fractured gneiss/schist bedrock to obtain a seal and consolidation grouting was unsuccessful, a modified cased system was advanced deep enough into the rock to eventually seal. The 3-#20 bars were changed to 12-strands since the bars wouldn?t fit through the smaller cased hole. The options were limited because each dolphin only had enough room for a small hydraulic drill rig that wouldn?t have the power to fully case the holes. The Canada Place Pier Extension in Vancouver?s Harbor led to the development of an innovative tip design used later at Vanterm. The 36? diameter steel pipe piles were driven closed end but modified to permit drilling through a concrete plug at the base. The driving of the piles at Canada Place often knocked out the plug so we were faced with 50 feet of sand up inside the pile when the drilling started. This led to discussions on how to safely remove the sand, solidify the tip, and continue drilling to get past the tip without undermining the pile. Finally, Vanterm Berth Extension was completed with a unique drilling system because the pile tips stopped in hydraulic sands, as opposed to the native till. We were faced with advancing the casing to the till without undermining the base of the pile. With 100 psi water pressure at the pile base after we broke through the concrete plug, the trick was to prevent charging the sand with our 250 psi air which liquefies it and forced it up our drill casing. And of course, it has to happen just before Christmas holidays!

Jan 1, 2004

By J. S. Megahan

This report covers the design, fabrication and testing of the first and second generation mechanical scaling bars for more safely removing loose rack from mine roofs and walls. Included are discussions covering a survey of mine conditions and presently used hand scaling bar types as well as the design, fabrication and testing of the first and second prototype.

Jan 1, 1982

The relationship between comminution testwork results and the milling circuit that is subsequently selected is not a direct one and frequently involves recourse to databases of past test results. This in itself reflects the lack of a systematic engineering approach in the design process. This paper reviews comminution tests for SAG mill design in an attempt to identify where the essential information comes from that will be used in mill selection. The conclusion is that results from traditional test methods, including obscure and little used procedures like the Mokken test, are more valuable from an engineering perspective than parameters for breakage rate based modelling. Suggestions are made on ways in which existing test procedures can be enhanced in order to generate parameters that can be directly related to characteristics of the milling circuit being designed.

Jan 1, 2002

A record $18.7 billion worth of metals, non- metals and fuels was produced in the U.S. during 1962, according to a year-end estimate from the USBM. The 1962 total value, based on preliminary statistics compiled by the Bureau, was nearly $600 million more than in 1961. Most minerals gained both in value and volume of production during 1962 according to information collected by the Bureau. All mineral fuels except anthracite showed increases. Among nonmetallic minerals- other than fuels-gains exceeded losses by two to one. Metal production held steady as gains and losses balanced.

Jan 2, 1963

By E. R. Maize

This report is the third of a series on convergence of roof and floor in coal mines and subsidence of surface that accompanies it. The first papery dealt with extraction in a mechanized mine (Montour 10) having relatively short rib lines that retreat rapidly. The second 6/ dealt with extraction in a mine (Crucible) in which coal was loaded by hand and in which the rib lines were long and slow-moving. The present report deals with a mine (Gibson) in which conditions approximated those in the Crucible mine, except that the distance between room centers was considerably less and the pillars were narrower in consequence. Moreover, the average cover was less and the studies were made under the steep hillside of a stream valley compared with a gently rolling surface over the portions of the second mine studied. Gibson mine lies in the east-central part of Washington County, Pa., approximately midway between the Montour 10 and Crucible mines on a north-south line. A cooperative agreement covering the work was made with the Hillman Coal & Coke Co. through W. L. Affelder, vice president. This paper describes the methods used in the investigation, gives excerpts from the data obtained, and offers such generalisations as appear to be justified.

Jan 1, 1940

By F. S. Crawford

"After many years of safety activity in the United States in one form or another it becomes increasingly evident to those in contact with safety work that to achieve continuous good results in accident prevention there must be an aggressive organization behind the safety movement at each mine with fairly definite plan and policy. A study of the methods used by various companies and the results they have attained will be of value to the common cause of safety promotion.A study has been made of the safety records of the Menominee iron range in the Lake Superior district, and of data from the county mine inspector's report. Several companies on this iron range that have attained a certain measure of success in their work of accident prevention have given data, and a summary of their safety methods is presented.The Menominee iron range of Michigan lies in the southern portion of the upper peninsula of Michigan, bordering on Wisconsin. It consists of two main. divisions--the West Menominee Range, situated in Iron County in the vicinity of Iron River and Crystal Palls, and the East Menominee range situated in Dickinson County in the neighborhood or iron Mountain, Mich. The mines about Iron River and Crystal Falls are peculiarly subject to fires in a carbonaceous, sulphur-bearing black slate which appears in the footwall. This gives considerable trouble because fires in this material start from spontaneous heating. The methods of mining are top slicing and open stoping, working on benches along the sides of the stopes. The character of the ground varies from medium Soft ore to relatively hard ore which permits open stoping. Approximately one-third of the operating mines are equipped with a fan for main mechanical ventilation. The remainder are ventilated by natural draft. The East Menominee range is the older, top slicing having been used there for a number of years, and the timber mats have boon well developed. In common with all districts, some companies pay more attention to safety than others, although, those which do riot have the best records do pay some attention to safety.During the past three years the annual production per man employed has remained about constant, but in many mines a general decrease is shown in the accident record. The variation in the results attained can be ascribed mainly to the earnestness with which accident-prevention work is pursued, essentially regardless of the method of mining used. This is shown to be generally true, because the record indicates a steady decrease in one mine with an active safety department, while in adjoining mines with the same kind of ground and method of mining but where not such intensive attention has been paid to safety work, the accident record is high."

Oct 1, 1931

By Mark Sanders

This report describes an experiment which was conducted to compare the relative bumping hazard of a low and high profile hard hat (helmet) in a low seam mining environment. The study was specifically designed to assess the effect of lowering the helmet profile on frequency of head impacts in an underground low seam coal mine simulator. This involved subjects performing four common low coal mining tasks wearing the low and high profile helmets in the low seam simulator (36" and 48? heights). The results of the study indicated that a low profile helmet could reduce bumping frequency in underground low coal approximately 25%, and as much as 80% on selected tasks. It was beyond the scope of the study to measure the impact force, thus it was not possible to estimate the effect of the low profile helmet on severity of impacts underground. The research team recommended that a more extensive investigation be made of head injuries experienced in low seam mining (both underground and surface) with the objective being to assess the impact of a low profile helmet on total head accident exposure.

Jan 1, 1980

By A. L. Foote

This is the final report of work accomplished during 1973-75 under U. S. Bureau of Mines Contract No. H0242015, "System for Handling Underground Mine Supplies and Materials." The purpose of the contract was to develop a mechanical device which could safely perform handling tasks that are normally done manually in underground bituminous coal mines. The report discusses studies leading to construct-ion of a battery-operated, three-wheel vehicle with a six-degree-of-freedom manipulator. Supportive design studies included collection and analysis of production, manual functions, and injury data on the underground bituminous coal mining industry. Transfer tasks in section storage and working places were the prime candidates for mechanical handling. Functional specifications were developed for two handling devices (one to handle existing unit loads and one to handle repackaged unit loads) and for a vehicle to mount the handling device. Design concepts for nine different handling devices were developed and a cost/benefit evaluation made for each. Detail design, capital and operating costs, and method improvement savings data were developed for two battery-operated vehicles and for two different manipulators. The three-wheel vehicle with anthropomorphic manipulator was chosen for development.

Jan 1, 1978

By Ángel Bravo

La simulación es un programa virtual que permite evaluar los costos de perforación y soldadura para el costo final del proyecto minero. El modelo fue diseñado en hoja electrónica, cuyos datos de entrada son estándares de perforación y voladura, tipo de equipo, ciclos de minado, ciclos de avance en túnel, método de explotación, sección de túnel, costos, etc. En este sentido, el presente texto describe el diseño de simulación que buscará determinar la flota óptima de jumbos, asi como la organización óptima para asegurar una máxima utilización de equipos y establecer un sistema de mantenimiento y servicio de máxima disponibilidad. Su función de probabilidad está orientada específicamente para un método de explotación o tunelería.

Sep 13, 2001

?Longhole blast hole drilling? techniques are not new to the mining industry. Appropriate mechanization and improvement of the techniques and application has evolved from the industry requirements. Today safety and economics play a larger role in the excavation of ore passes, ventilation passes, and relatively small inclined excavations in the conventional gold and platinum industry. The application of dropraise drilling from the top or from the bottom is discussed investigating the current techniques available, DTH application, advantages and disadvantages, limiting factors, typical layouts and proposals, the drop raising technique and future applications. Similarly, the application of longhole blast hole drilling in tabular and massive orebodies is discussed with emphasis on the DTH application, advantages and disadvantages, limiting factors, typical layouts, the long hole stoping techniques and future applications.

Jan 1, 2003

The investigation summarized in this report addressed two primary issues: the determination and use of correction factors, and the development of guidelines for velocity measurement site selection. Other ancillary issues which were addressed include a comparison of measurement methods and devices, aircourse cross-sectional area measurement, and characteristics of mine airways. An exhaustive literature search and analysis was performed; extensive in-mine experiments were conducted; a quantitative analysis of the data was used to develop correction factor tables and site selection guidelines. The reported results of other researchers who have examined the correction factors and site selection criteria, were analyzed in light of the results of this study. The measurement devices included in the experimental phase were: vane anemometer, vortex shedding anemometer, a prototype thermoanemometer, smoke tube, and, oil of wintergreen. The measurement methods include single-point centerline, timed¬-point traverse, continuous traverse for the anemometers, and various distances and cloud positions for the smoke tube and oil of wintergreen devices.

Jan 1, 1983

By Philip Thompson

The Bureau of Mines investigated a selective flocculation-flotation technique to remove insoluble slimes from low-grade potash ore in a continous 45-kilogram-per-hour (100-pound-per-hour) process investigation unit (PIU). This research is part of the Bureau's program to improve resource recovery from low-grade ores. Results showed that 84 percent of the insoluble slimes were removed from an ore containing 5.5 percent water-insolubles and 14 percent K20 using a Bureau-developed, cationic flocculant-glycol ester-diesel oil reagent. Subsequent potash flotation recovered 75 percent of the potash in a cleaner concentrate assaying 56 percent K20. Concentrate leaching upgraded the product to market specifications of 60 percent K2O. An economic evaluation by the Bureau suggested that the rate of return on investment, after taxes, should be about 20 percent for such an enterprise.

Jan 1, 1980

By Sean Gallagher

Bolting large sheets of wire mesh screen (WMS) to the roof of underground mines prevents injuries due to rock falls. However, WMS can be heavy and awkward to lift and transport, and may result in significant spinal loading. Accordingly, six male subjects (mean age =45.8 years + 7.5 SD) were recruited to lift WMS in a laboratory investigation of the biomechanical demands. Biomechanical modeling was used to estimate external moments about L5-S1 for sixteen lifting tasks, using two sizes of WMS. Full-size WMS involved a two-person lift, while half-size WMS involved a one-person lift. Lifts were performed under 168 cm and 213 cm vertical space. Restriction in vertical space increased the maximum L5-S1 extensor moment from 254 to 274 Nm and right lateral bending moment from 195 to 251 Nm. Lifting full sheets of screen (as opposed to half sheets) resulted in an average 33 Nm increase in L5-S1 extensor moment. The L5-S1 extensor moment was increased by an average of 44 Nm (18%) when lifting screens positioned flat on the floor compared to an upright position. Relevance to industry: Large flexible materials are commonly lifted in industrial work environments, and may involve the efforts of two or more workers. The current study examines the low back loading associated with lifting large flexible screens and presents recommendations to reduce spine loading.

Jan 1, 2009

By D. Linzey

"History of Whitehorse Copper BeltThe first discovery of copper on the Whitehorse Copper Belt is reported to have been made by miners on their way to the Klondike in 1897. By 1899 the district had been well prospected and many of the presently known deposits had been staked.The first shipment of ore was from the Copper King property in 1900. This consisted of 9 tons of hand picked ore grading 46.4% copper. It was not until the period between 1912 and 1917, the production years of the Pueblo Mine, that significant ore shipments were made. Total production was 140,000 tons at 3.5% copper. An underground disaster killed six men and closed the mine in March 1917.Although the general area was dormant until after World War II, by 1947 geological mapping, magnetic surveys and diamond drilling had been done on the important showings. In 1954 Mr. Aubrey Simmonds directed the formation of Imperial Mines and Metals, which acquired by option and staking a large part of the Whitehorse Copper Belt. In 1957 Mr. Arnold Pitt reorganized the company as New Imperial Mines. With financing from Sumitomo and Toronto-Dominion Bank, a mill was built and production was started from the Little chief orebody by open pit in 1967."

Jan 1, 1977

By Michael M. Hamilton

In 1984 and 1985 the U.S. Bureau of Mines performed a mineral survey of the South Jackson Mountains Wilderness Study Area covering 60,211 acres of mountainous terrain of Humboldt County in northwestern Nevada. Approximately 550 lode claims have been located within or adjacent to the study area from 1900 to the present. Total recorded production for the area is 28.19 ounces gold, 1,105 ounces silver, 959 pounds copper, 6,016 pounds lead, and 12,446 pounds zinc; an additional two carloads from one mine contained an unknown amount of metal. In early 1986, there were eight active properties with a total of 126 claims. Wescord Resources and Long Lac Exploration (Texas) Inc. are involved in a joint exploration of the Jackson Mountains for volcanogenic massive sulfide deposits. Development at the Claudia mine continues in 1986. Results of the survey indicate that there are no identified mineral resources or reserves within or adjacent to the study area. Twenty-two properties have mineral occurrences containing gold, silver, copper, lead, zinc, iron, antimony, vanadium, and cobalt, with silver, copper, and iron being the most abundant.

Jan 1, 1987

By T. T. Read

JAPAN'S iron and steel industry has always been closely connected with military strategy. Many years ago it became evident that the country's iron-ore resources were too small to support any extensive industry. As a result a belief in the imperative necessity of securing such resources has influenced Japan's political and economic policy in the Far East. Iron-ore developments in China are too well known to need repeating except to note that they have been rather unsatisfactory to both China and Japan. The ore deposit at Tayeh, in China, is not as large as was first believed and, though that and other sources of supply in China proper are now furnishing Japan a little more than a million tons of ore yearly, it cannot be counted upon as a large permanent source of supply. The deposit in Shantung proved so disappointing on further exploration that operations there have, so far as I know, long since ended. The operations at Pen-bsi-hu, in South Manchuria, which C. F. Wang de¬scribed in the A.I.M.E. TRANSACTIONS for 1918, Vol. 59, were reported to have yielded 84,000 tons of pig iron in 1928 and about 50,000 in 1935, so they seem to be going back.

Jan 1, 1937

By Walter Frank

The purpose of the work covered by this contract is to develop a ground and pilot conductor connector which will significantly improve mine trailing cable splice performance. This work compliments the work completed under Contract 00357100 on the development of crimp connectors for the phase conductors of trailing cables. A brief discussion on splice problems is presented as an introductory means and substantiates the need for the development and test programs outlined in this report. As with the phase development work, the ground and pilot connector work is essentially of an empirical nature. As a result time is devoted to explaining the derivations of the test procedures used. In order to familiarize the reader with connector terminology a section is devoted to a glossary of pertinent terms. The connector design effort includes connectors for splicing ground and pilot conductors. A distinction is made between connectors suitable for splicing round and flat ground configurations. The same also applies to the pilot conductors. During the course of this work, much time has been devoted to the question of suitability of round cable configurations for trailing cable applications. This is discussed in detail along with resulting conclusions and recommendations. A field test program was conducted in order to confirm ground and pilot connector laboratory data. This testing also determined the viability of the connector designs and recommended installation techniques in a mine environment.

Jan 1, 1979

By R. J. Traube

The purpose of the Inherently Safe Mining System (ISMS) project is to develop continuous and conventional coal mining equipment and systems which will reduce the incidence of fatal and nonfatal accidents in the working sections of underground bituminous coal mines by application of existing technology. This 3-year program, initiated on 18 June 1971, is being conducted in three phases: ? PHASE I (8 months) Systems Analysis Concept Design Planning ? PHASE 11 (16 months) Design Procurement Manufacture Preliminary Testing ? PHASE III (12 months) Underground Coal Production Demonstration.

Jan 1, 1972

By Gordon Miner

GENERAL DESCRIPTION At the Star mine, Hecla Mining Co., located in Burke, Shoshone County, ID, the mining method is horizontal slicing (timbered or untimbered) cut-and-fill using hydraulic sand backfill. Back stoping as well as breast stoping is used; see Fig. 1. The annual produc¬tion from all cut-and-fill mining is 259 816 t (286,400 st). The average depth ranges from 366 to 2408 m (1200 to 7900 ft). A majority of the tonnage comes from an average depth of 2240 m (7350 ft). Average travel time to the stope is 1 hr. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size and Ground Conditions The ore body is 610 to 1219 m (2000 to 4000 ft) along the strike and 2408 m (7900 ft) on the dip, with an average vein width of 2.6 m (8.5 ft). The dip is essentially vertical. The ore body is heavily sheared and broken on the main fault structures; it is more competent on the wall veins but everywhere subject to rock bursting at depth. The hanging and footwalls are strongly fractured on the main fault structures, again more competent but still fractured on the wall veins. All host rock is Revett quartzite. Value and Production Requirements The ore value is $56 per ton. Production require¬ments are 1089 t/ d (1200 stpd), five days per week. Why Cut-and-Fill? The slusher extraction method is the most satisfac¬tory and practical for narrow vertical veins with sheared walls. The method must be quite selective to be com¬mercial. The veins are too narrow for rubber-tired ex¬traction and the grade is not high enough to make resuing practical. DETAILED DESCRIPTION Development Access to the main shaft is by the 3.2-km (2-mile) main haulage tunnel. The level intervals in the vertical timbered shafts are 61 m (200 ft). Vein development is by crosscut and laterals located 30.5 m (100 ft) into the vein wall. Vein crosscuts are on ±61 m (200 ft) centers. Access to the vein is by raises carried up with the stope. The raises are equipped with four wood¬cribbed chutes (two orepasses reinforced with angle irons, one manway, and one timber slide, Figs. 2-6). The initial cut is located 6.7 m (22 ft) above the main level (Fig. 1). Stoping Cycle Detail Sampling: Grab samples are taken from the mine cars. Channel sampling of the faces and backs is done when necessary. Drilling: For stope drilling, Ingersoll-Rand 300M percussion drills are used, with Ingersoll-Rand 300M and Gardner-Denver RB83M stopers, used for back stoping. Breasting down is done with Gardner-Denver S83FM jacklegs. The back stoping rounds are 0.9 to 1.8 m (3 to 6 ft) and the breast stoping rounds 1.5 to 3m (5 to 10 ft). Blasting: For stope blasting DuPont Tovex 100 watergel with fuses and igniter cord is used primarily. Approximately 60% of the blasting is done with am¬monium nitrate-fuel oil (ANFO). For development headings and shaft sinking, DuPont Drivex watergel with Ensign Bickford Nonel Primadet primers is is used. Mucking: Broken ore is removed entirely by slusher in the stopes. These are mostly 3.7-7.5-kW (5-10-hp) Ingersoll-Rand air-powered or 7.5-37.3-kW (10-50-hp) Ingersoll-Rand electric-powered. In the horizontal de¬velopment headings Eimco 12B and 21 and Atlas Copco LM-56 overshot mucking machines and a 0.76 (1 cu yd) hydroelectric Wagner HST-1 LHD (load-haul-dump) unit are used. Rockway for Extraction: The cribbed chutes (Fig. 7) are nearly vertical and hexagonal in shape and are made of spaced 152 x 203-mm (6 x 8-in.) timber, reinforced with varying weights and sizes of angle iron, depending on wear requirements. Rectangular cribbed chutes are used where ground pressure is not a problem. Cribbing is added in 2.4 or 3-m (8 or 10-ft) extensions accord¬ing to the floor height (whether timbered or untimbered). See Figs. 8 and 9. Backfilling: Backfilling is done with hydraulic sand consisting of classified mill tailings at 65% solids. The fill contains approximately 20% 325-mesh fines. The tailings are pumped 3353 m (11,000 ft) at 50-55% solids 22.7 dry t/h (25 dry stph) with a duplex piston pump. Cycloning increases the tailings density to 65% solids. Fill storage is in a 998-dry-t (1100 dry st) agi

Jan 1, 1982