Search Documents

By Kevin Phelan, Gary Johnson, Peter Sperring

The vast majority of tailings in the Western Australian Goldfields are deposited in purpose-built storage facilities. At mine-sites with open-pit mining operations there is also the requirement to mine and stack large volumes of waste rock, usually into surface waste dumps. As these dumps have typically 30% of their gross volume present as voids, there is the potential to use this void space for the storage of tailings. The concept of co-disposal is to store the tailings material in the void space of the waste dumps, eliminating the need for a separate tailings storage facility. Dominion Mining Limited have been investigating the possibility of using co-disposal as a means of tailings storage. Laboratory testwork has been used to understand some of the issues associated with the concept, and assist in the design of an on-site demonstration of the concept. Co-disposal offers a number of potential advantages, and despite a number of practical hurdles to overcome, considerable economic and environmental benefits could be realised if this concept can be demonstrated on a commercial scale. The major advantage of such a system is to remove the need to build, operate and rehabilitate a separate tailings storage facility. Rehabilitation can be incremental throughout the mine life as the co-disposal site will be virtually indistinguishable from a current waste dump in both size and form. Other potential advantages include more stable waste dumps, less land area disturbed on the project site, and better water recovery from the tailings.

Jan 1, 1995

By S. Tavani, R. E. Browner, R. Dunne

Lead is used in CIP/CIL circuit to increase the leaching rate of gold from ores. At least four mechanisms have been proposed for the action of lead in gold leaching circuits: (I) precipitation of sulphides as highly insoluble lead sulphides preventing consumption of cyanide and oxygen; (2) su,face reaction on sulphide particles forming an insoluble lead sulphide layer peventing dissolution of those sulphides; ( 3) precipitation of lead sulphide, which undergoes further oxidation to soluble lead sulphate recycling the lead to solution,· ( 4) contact reduction of lead onto the gold szaface which then acts as a secondary oxidising agent. Rotating disc studies using a pure gold disc show that small amounts (5ppm) of sulphide ions are sufficient to significantly reduce the leaching rate of gold. Lead increased the leaching rate at small concentrations but at higher levels decreased the rate of leaching. The detrimental effects of lead were only found for a pure solution when leaching the gold disc. Ores mediate the amount of lead available by ads01ption/reaction, thus, reduced leaching rates from excess lead are not serious even when 500ppm of lead ions are added to the sluny. The detrimental effects of sulphide ions could be countered by lead addition during the leaching process. A penalty, in the form of reduced leaching rate, will occur the longer lead addition is delayed. A time lag was noted between the addition of lead and the increased leaching rate when a large concentration of sulphide ions was present.

Jan 1, 2000

By Herb Wilson

The Klondike symbolized one of mankind's driving forces - the desire to lay one's hands on a scarce resource, gold, in that case - and in doing so to make some money along the way. It can be argued that construction aggregates - a once lowly and ignored sector of the natural resource industries - have become the desired targets of their own "Klondike." This began in the 1970s and accelerated to a frantic pace in the 1980s. The scope of industrial minerals is very wide. It ranges from high value minerals such as talc, bentonite and kaolinite to the truly humble minerals of sands and gravels, limestones and granites. Their major end uses are in construction aggregates. A rich variety of different mineral types all make good construction aggregates. However, those successfully used have two fundamentals in common: • Their technical characteristics are appropriate for the requirements of their end use. • They are located within an economic distance from the market. The North American market This is the largest construction ag¬gregate market in the world. Consumption in 1990 reached 2.2 Gt/a(2.5 billion stpy). This rate of consumption has grown steadily over the past decades. In the United States, from 1963 to 1989, it averaged a 1.6% compound growth rate. Within this long-term trend, there are business cycles, because aggregate demand is closely linked to economic strength or weakness. The North American market also displays the greatest per capita demand for aggregates when compared to the major industrial economies (Table 1).

Jan 1, 1993

By P. Anciaux

The EUs? manufacturing and construction industries are vital to Europe?s economy. They rely heavily on a steady supply of materials which meet appropriate quality criteria and are available at a competitive price. The steadily rising global demand for (non-energy) raw materials due to increasing consumption in upcoming economies such as China, India and Brazil, is in some cases leading to rapid price increases, but also supply disruptions which affect the European industry chain. These considerations are at the basis of new policy initiatives that are being prepared by Enterprise and Industry Directorate-General in relation to the competitiveness of the European metals industry. Over the last year the raw materials supply issue has increasingly become the topic of de-bate among various stakeholders. In July 2006 the European Economic and Social Committee adopted an opinion on risks and problems associated with the supply of raw materials to European industry. It is therefore important to identify and analyse the future needs for European industry, the possible constraints and impacts on its competitiveness. The raw materials supply issue should also be looked at from the view-point of the EU extractive industry, which plays an important role in supplying raw materials to the downstream industries and which faces very specific challenges. Within the Enterprise and Industry Directorate-General the different factors that influence the competitiveness of the non-energy extractive industry are being assessed, in order to help identify policies and actions which could contribute to and enhance the competitiveness of the industry.

Jan 1, 2007

By J. J. K. Daemen, C. Fairhurst

Two aspects of tunnel support design are considered, and for both particular attention is paid to the influence of rock failure around the tunnel on the loads developed on the supports. 1) In general it has not been possible to extend analytical methods for the study of rock failure around tunnels to three dimensions. As a consequence it was not possible to calculate either the influence of the face or the actual sequence of support loading as the face advanced. The finite element method made this extension possible. A simplified analysis of the influence of the face and of the sequence of support installation has been made. The influence of the original stress field and of the rock behaviour on the length of tunnel which can be left unsupported (related to the stand-up time) is shown. The degree to which a 2-dimensional analysis can be used to approximate the final support load is shown to be dependent upon the post-failure behaviour of the rock. 2) Tunnel support design requires a knowledge of the forces and of the -rock displacements which cause stressing and deformation of the support system. A 2-dimensional model incorporating a detailed representation of several support systems, of the rock behaviour in the broken zone and of the interaction between rock and support is given. The model allows the calculation of the stress distribution in the support. The significance of the relative stiffness of support and rock on the stresses developed in the support is shown.

Jan 1, 1997

By S. Ubaldini

Acid mine drainage (AMD) is a common problem in different areas with a past history of mining activities, which is characterized by low pH (2-4.5) and significant toxic metals concentration. The main aim of the present work was to perform a process feasibility analysis in order to remove heavy metals (Cd, Zn, Ni, Mn, Cu) from AMD (Acid Mine Drainage) in a relatively cheap and environmentally friendly way, by means of electrowinning and biosorption. A first characterization of an Italian AMD sample was performed evidencing a zinc concentration around 2 g/L, cadmium and nickel content of about 4 mg/L, manganese of 85 mg/L and iron 190 mg/L. Electrowinning tests lead to the following metal removal after three hours treatment: Zn 99%, Ni 99.9%, Cd 99.9%, Cu 99%, Mn 87%, Fe 96%. Moreover, an high grade of purity of the metal deposit has been achieved (Zn>95%), as observed by X-ray diffraction analysis. Considering that metals concentration in the effluent was still above legal limits (in particular for Zn, Mn and Fe), a further biosorption treatment was planned in order to produce an effluent fitting environmental limits. Experimental electrowinning tests and literature multimetal column biosorption data have been used in order to perform a preliminary techno-economic feasibility analysis of the process aimed at metal removal from AMD. A treatment cost of about 6.5 ?/m3 AMD has been estimated, for a plant capacity of 10 m3/h AMD inlet flow rate.

Jan 1, 2006

By K. L. Kayler

Ball clay production in 1991 amounted to about 800 kt (880,000 st), about the same as in 1990. 1992 estimates show a 5% decrease to 750 kt (827,000 st). This decrease continued a trend of reduced production that began after the peak of 900 kt (1 million st) that occurred in 1988. Use of ball clay in sanitary ware was about 2% less in 1992, although levels of use in floors and wall tile, dinner ware and pottery remained constant. Filler, extender and binder applications continued to be important end uses, accounting for about 17% of total market. Refractory uses maintained their market share of about 17 kt (18,700 st). Use of clay liners in toxic and waste dumps is an application widely found in Germany. However, its use has not been fully exploited in the United States. This could represent an opportunity for domestic clay producers. Tennessee remained the leading source of ball clays. Other producers were Indiana, Kentucky, Mississippi and Texas. Tennessee's production, however, decreased about 3% in tonnage produced and its value dropped from 68% to 65% of total production. The ceramics division of Southern Clay Products, Inc., was bought from LaPorte plc by United Clays of Texas, Inc., a US subsidiary of Watts Blake Bearne & Co. The purchase included ball clay reserves at Troup, TX. The acquisition makes United Clays the second largest ball clay producer in the United Sates. United is also the only company mining clay in Texas. Fire clay production decreased 5%

Jan 1, 1993

This research contributes to BioMinE (http://biomine.brgm.fr), an integrated European Union project of the Sixth Framework Programme. The general objective of BioMinE is the development and integration of innovative, environmentally friendly, biohydrometallurgical processes for the recovery of metals from primary and secondary resources within Europe. The work presented in this paper deals with the initial plan of study on the sustainable use of solid wastes derived from bio-processing of European metal bearing resources. The approach involves solidifying the waste into cementitious waste composites analogous to controlled low-strength materials (CLSM). The aim is to achieve composites of adequate mechanical, physicochemical and environmental integrity, thus providing a sustainable solution for dealing with such bulk products which are conventionally unmarketable and therefore normally discarded to landfill. Assessment has been based on largely ?model? wastes anticipated to be similar to bio-processing wastes. These include an ochreous mine water sludge and an industrial goethite residue. The work indicates that wastes containing high iron and calcium contents, typical of products from bioleaching of concentrates, could be beneficially reformed as CLSM of appropriate compressive strength. Due to the high water contents of these composites, porosity and hydraulic conductivity were correspondingly high. Flow-through leach tests showed some resistance to immobilisation of toxic elements. Work is continuing to reduce the risk of toxic elements leaching under environmental conditions. This will include laboratory-scale encapsulated systems of CLSM, designed and tested to produce a novel type of engineered fill structure.

Jan 1, 2006

By S. Serata

Background Results of the above study in the August 1991 issue of Mining Engineering offer valuable lessons in the solution of cutter-roof problems. The original study plan was initiated by the discussion authors to solve the problems using the "stress control method" of mining (Serata 1976,1982; Serata, Carr and Martin, 1984; Serata and Gardner, 1986; Serata, Gardner and Preston, 1986; Serata, Gardner and Shrinivasan,1986; Serata and Kikuchi, 1986; Serata, Preston and Galagoda, 1987) However, the plan and the planner were changed to the arrangement reported in the paper. The change was considered reasonable at the time due to the mine engineers' uncertainties about the stress control method. Consequently, the basic principle of the study was shifted from the original stress control method to the method described in the paper, which will be called the "yield pillar method" for the purposes of this discussion. The paper convinces the reader that the yield pillar method fails to solve the cutter-roof problems. This doesn't mean that the stress control method also fails. Actually the contrary is true, as discussed below. Limitation of the yield pillar method The paper illustrates clearly how poorly the yield pillar method performs in solving the problem. The reason for this failure is the lack of the protective stress envelope needed to stabilize the cutter roof. Unfortunately, the protective envelope cannot be formed properly without utilizing the stress control method of mining. Changing the pillar size does not make much difference in the roof stability.

Jan 1, 1992

By D. C. Willett

INTRODUCTION The Symposium on the Development of Underground Space, held in Seattle, Washington, from October 1 through 3, 1980, was organized by the "Deep Space" subcommittee of the ASCE's Underground Research Technology Council. The primary objective of the symposium was the exploration of the interfaces between the investigation, design and construction of large underground facilities in "deep space" which, for the purposes of the committee, has been defined as starting at 100m below ground surface. The meeting focussed primarily on tunnels, caverns and shafts in hard rock; the meeting format comprised a number of brief presentations concerned with the technical aspects of investigation, design and construction, followed by an open discussion, and concluded with the assembly of recommendations regarding the interface problem by the symposium participants. The principal considerations brought out during the symposium, and a general review of the conclusions, are briefly presented in the following paragraphs. INVESTIGATION The sessions dealing with "Investigation" were chaired by Dr. H. Pratt. Presentations were made by Dr. D.C. Banks, Dr. W.A. Hustrulid and Dr. Pratt. The extent of the interface of the investigation phase with the other (design and construction) phases of an underground facility will depend in large measure upon the nature of the facility; at one end of the spectrum, the investigation must be in continuous and closely coupled relationship with the design of a radwaste facility. At the other end of the spectrum, for (say) a small mining operation, the interface is largely associated with the initial development, with only minor on-going involvement.

Jan 1, 1981

By B. D. Hong

The Coal supply and demand review arrived too late to appear in the May issue. In 1991, the US coal industry produced 902 Mt (994 million st) of coal, according to preliminary data compiled by the Energy Information Administration (EIA) (Table 1). This amount was 32 Mt (35 million st) less than the record 933.5 Mt (1 billion st) produced in 1990. Most of the decrease in coal production occurred east of the Mississippi River. The substantial stock buildup that stimulated production in 1990 was not repeated in 1991. In addition, coal consumption by electric utilities and coke plants dropped by about 1.8 Mt and 4.5 Mt (2 million and 5 million st), respectively. Moreover, a higher level of coal exports failed to bolster the 1991 production. Production Surface mines accounted for about 59% of the 902 Mt (994 million st) of coal produced in 1991. Underground mines produced for 41%. More than one-fourth of the total coal output was from federal and Indian coal leases. Production of all ranks of coal, except subbituminous, declined in 1991. Bituminous coal is produced mainly in the East. It totaled an estimated 590 Mt (651 million st), a 6% decrease. Production of subbituminous coal, mostly in the West, rose 3% to a record 228 Mt (252 million st). Lignite output was from Texas and North Dakota. It decreased by 1 % to 79 Mt (87 million st). Anthracite production, all from eastern Pennsylvania, fell by 17% to 2.7 Mt (3 million st).

Jan 1, 1992

By H. Lyn Bourne

This is the eighth annual tabulation of royalty information. Again this year, some of the older information has been deleted to make room for nearly 30 new entries. Several articles and publications have appeared recently that relate to mineral royalty or mineral valuation. R. B. Parsons wrote "Mining agreements, royalties and profits" (CIM Bulletin, November 1988). He distinguished between net smelter return (NSR) and net profit interest (NPI). Parsons used examples to show the difference between these royalty payment methods. Mining Engineering (January 1990) carried an article by H. V. S. Tingley entitled "Using business due diligence to help evaluate mineral deposits." The article identifies some factors that must be examined during mergers or acquisitions in the mining industry. Since each mining operation is unique, each has risks and opportunities that need recognition and evaluation. The author suggests that a team is necessary for a proper evaluation because no one person has expertise in all of the factors that must be examined. Also in January's Mining Engineering was "Limestone mining: Reserves and valuation," by B. C. Lewis and R. P. Moran. They presented two case studies of valuation of limestone reserves. One was a 109-hm2 (270-acre) parcel in West Virginia and the other a 121-hm2 (300-acre) tract in Alabama. The authors discussed risk, discount rates, and royalty methods as financial parameters in valuation of limestone reserves. Two papers were presented at the SME meeting in Las Vegas, NV in 1989 that bear mention. J.G. Russell's talk was entitled "Valuation of industrial

Jan 1, 1990

By S. C. Suboleski

Underground long-range planning and mine design is an iterative process beginning with a specified production level, quality criteria, and geology of the deposit. Given these factors, face equipment is selected, the number of units needed and production per unit are calculated, and the mine infrastructure needs are developed. The scheduling of units then follows, with the design of the various support systems coming next. The support systems needed to maintain production can be grouped as follows: (1) outby haulage of mined material, (2) supply and manpower haulage, (3) ventilation and associated environmental considerations, (4) drainage, fresh water, and related considerations, (5) rock mechanics, and (6) power, supply. Thus, long-range planning may be viewed as a three-tiered structure, with the data on required production, product quality, and geology at the upper level; the development of face production capacity and the scheduling of units sufficient to meet the needs of the first two at the second level; and the development of support operations for the production units at the third level. Changes at any level may affect not only the items on that tier but may also cause a change to the items on the tier above and below. For example, if the rock mechanics data indicate that desired opening sizes will not be stable, then this situation will affect not only the ventilation design but also the production rate and possibly the selection of equipment itself. These, in turn, may affect the scheduling of units and the number of units, ultimately influencing the entire third tier of systems.

Jan 1, 1979

By H. Verakis

A fire in a coal mine conveyor belt entry represent a major safety and health risk to miners. Fighting belt entry fires can be a commanding effort. If there is a failure of one aspect in the fire fighting needs such as a dissimilar hose-valve connection, then it can result in the inability to extinguish a fire. Fire incident data compiled over nearly 30 years for underground coal mines shows that fires in belt entries account for 15-20 percent of the total number of fires. Fires in the belt entries of coal mines have resulted in injuries and fatalities. New regulations have been promulgated that require an unplanned fire not extinguished within 10 minutes of discovery to be reported to the Mine Safety and Health Administration (MSHA). A fire that is not extinguished within several minutes may take hours or days to extinguish or may require sealing a section or the mine in some cases. The current fire protection regulations in the U.S. Code of Federal Regulations (CFR), Title 30, Part 75 are designed to prevent or control the fire hazards present in a belt entry. These requirements and other factors affecting belt entry fires are discussed, including fire detection and warning, fire suppression devices, type and location of fire fighting equipment, waterlines, and cleanup and removal of combustible materials. The fire suppression systems used to extinguish/control a belt fire and the effect of ventilation on the propagation of conveyor belt fires are also discussed.

Jan 1, 2009

By Charles E. Joachim

Current Army tunnel destruction criteria (1) are based on limited nuclear-explosive (NE) and high-explosive (HE) test data. The PILE DRIVER (2) and HARDHAT (3) events investigated tunnel and support system response where yields were relatively large and tunnel diameter small compared to typical underground openings and localized stress fields of low yield weapons. Some limited tunnel destruction information was obtained from underground events of the PLUMBBOB and HARDTACK II Series (4). These events used access drifts which were designed to be self closing at the weapon point. The limited NE data are augmented by HE results from the Underground Explosion Test (UET) Program, a series of model and prototype-scale experiments in granite and sandstone (5). Weapon standoff distances (charge c.g. to tunnel wall) were at or near the maximum for major damage. Limited tunnel destruction was produced by a series of hasty and deliberate tests (6) on abandoned railroad tunnels in basalt. Additional HE data were obtained from model tests at the Waterways Experiment Station (WES) (7) using 2.1 MJ (2 lb) TNT charges and tunnel diameters varying from 3 to 17 cm (1.2 to 6.6 in). Recent laboratory scale HE experiments (8) conducted at the WES under the ESSEX program investigated the effects of tunnel diameter, standoff distance, charge confinement, material strength and to a limited extent, tunnel spacing and liner strength variations on tunnel damage. This paper summarizes the analysis conducted to develop predictions for the effects of low-yield nuclear weapons against tunnels and underground openings in rock.

Jan 1, 1979

By Donald K. Sparling, C. Edwin Baker

The White Mesa uranium/vanadium mill is six miles south of Blanding, UT, on the Colorado Plateau, which has historically spawned more than 200 uranium mines. As uranium prices approached an all-time high during the mill planning period, Energy Fuels Nuclear Inc. anticipated the reopening of many of these mines, whose low grade ore suddenly looked economic. The company located the White Mesa mill close to these mines, to minimize hauling distances to the mill and give vendors added incentive to reopen or expand mine operations. A receptive local community, a relatively unencumbered trip through the regulatory maze, and some mill circuit innovations all helped to make the White Mesa mill a well functioning reality. From a strategic standpoint, and to begin ore stockpiling as early as possible, Energy Fuels constructed two ore buying stations and began receiving ore in early 1977. The buying stations were located at Hanksville and at what is now the Blanding mill site. Ore receipts at Hanksville did not materialize as anticipated and the facility has since been closed. The Blanding ore buying station is now an integral part of the milling operation. All ores, whether company, vendor, or for toll milling, are received at the Blanding station. The Blanding site was central to the plateau mines, and was well received by area residents, who encouraged the introduction of industry to the area. Residents viewed mill construc¬tion as an economic blessing and were prepared to accept the associated im¬pacts. Energy Fuels hired as many local people as possible for mill opera¬tions.

Jan 4, 1981

By Chapman Young, Donald E. McCarthy

Many hard rock tunneling projects, where the majority of excavation can be accomplished with TBMs, will still require considerable specialized excavation which can not be done with a TBM. This secondary excavation, involving cross cuts, galleries, flattening of the invert, increases in bore diameter, et cetera, may be accomplished with conventional drill and blast, applied on a small scale and usually with fracture control techniques, or with mechanical splitters. The problems of using explosives in many of these cases and the high cost of mechanical splitting excavation make the consideration of other approaches attractive. The PCF rock excavation method, which has recently been reduced to commercial practice for mine-development excavation, offers an attractive alternative to drill and blast and mechanical splitters. With the PCF method the rock is excavated utilizing a small-charge, propellant-driven, controlled, penetrating-cone fracture process. Excavation is carried out continuously by combining the PCF hardware with integrated mucking capabilities on a carrier which remains at the excavation point. In addition to the benefit of providing for complicated excavation geometry, the PCF method also causes minimal damage to the remaining rock which will significantly reduce ground support requirements. In very bad ground, the continuous nature of PCF excavation allows ground support to be applied as limited sections are exposed thus reducing both the duration and extent that the ground would be free to move. Data on PCF excavation parameters, as measured in actual mining operations, indicate that crosscuts, galleries and the like could be excavated at considerable cost savings compared to drill and blast or mechanical splitters.

Jan 1, 1995

By John W. Rushton

THE PLANNED MAINTENANCE PROGRAM All concentrators should start with a planned maintenance program from day one. Every- body thinks they have a program in place before start-up, but in reality, most have only a fraction of what is needed to avoid the "Post Start-up Disaster" (PSD) - two years for start-up is not that uncommon. An effective program has all of the following: (1) Good people. (2) Area Maintenance. (3) Good PM Checklists. (4) Daily Work Schedules. (5) Written Work Orders. (6) Equipment Histories. (7) Backlog Control. The installation of a workable program takes hard work, talent, and commitment. You have to know what you are doing (hard work will not replace talent). Good People Good people are available in any location if you make the effort. Always check references carefully (both superiors, peers and subordinates). Was the last concentrator they worked at successful? Was it clean? Find out! Success or failure follows people around. I know people who are experts on PSD because they have lived through it three or four times. You need some college trained people with hands-on experience. There are no secrets, you have to make the effort. If you make a mistake in hiring (and you probably will), make the tough decision necessary to rectify it quickly. Area Maintenance Area maintenance refers to organization of supervision such that one person is uniquely accountable for every inch of ground and piece of equipment. Avoid overlapping authority if at all possible. You must have a planner as a staff position. A foreman cannot effectively plan and

Jan 1, 1986

Traditionally, production volume has been considered the major determinant of cost. As volume increases, total cost increases but unit cost decreases. This concept has been so widespread in industry that many of the tools used to analyze costs are based on production volume as the sole measure of activity and driver of unit cost-fixed and variable costs, cost-volume-price and breakeven analysis, contribution margin, flexible budgets, and others. Clearly, volume is a driver of cost. It is important in both a tactical sense (to the manager at an operating mine) and a strategic sense (as one determinant to the firm's overall cost position). However, many other factors influence costs as well, even though they have not been studied to the same extent. For example, production managers know that their costs will be reduced if the workforce does not have accidents. Safety costs are to a large extent independent of volume. Other cost components increase as volume increases, such as some environmental charges. Some costs may or may not reflect volume changes. Maintenance, for example, may appear as either a fixed or variable cost, as can operating labor in facilities that are highly automated. In the strategic sense, where the firm is selecting a strategy to pursue competitive advantage and increased profitability, all costs are variable. This reflects both the strategic intent and the long-term time frame associated with strategic positioning. Tactically, on a month-by-month basis, some costs are essentially fixed. Cost driver analysis must therefore consider the relevant time frame.

Jan 1, 1999

By Robert D. Talvensaari

It is indeed an honor for White Pine, as a member of the copper mining industry, to participate in this Rapid Excavation Conference. Although our presentation, as the title indicates, is not a success story, we foresee, through our experience, future application of boring machines and rapid excavation equipment in the hard rock mining industry. One might ask what a copper mining company would be doing with boring machines and why the gamble on a high-cost, capital investment for a relatively untried application. Perhaps a little background on the White Pine mine and its geology will explain our daring and speculative motives. THE WHITE PINE MINE The White Pine Copper Company, a wholly-owned subsidiary of Copper Range Company, operates a mine, mill and smelter at White Pine, Michigan in the western Upper Peninsula approximately 6 miles due south of Lake Superior. We employ approximately 3,000 people from the surrounding area and mine approximately 25,500 tons of low grade (1%) copper ore per day. The orebody is contained within several distinct sedimentary horizons that comprise the lower 20 feet of a Precambrian formation known as the Nonesuch Shale. Numerous articles and reports have described many aspects of the White Pine operation and the geology. I will brief you only on that criteria which precipitated our interest in rapid excavation equipment and techniques, specifically, boring machines. Mineralogical and optical studies have demonstrated that the siltstones, sandstone and shale beds all contain relatively barren and discrete particles of quartz (25%), feldspar and mica, bonded with

Jan 1, 1974