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General economic conditions continued to improve in the second quarter of 1984 as real gross national product advanced at an annual rate of 7.5 percent (table 1). This followed an even larger first quarter annual rate increase of 10.1 percent. The slower second quarter growth was greeted as a sign that the economy is not over-heating. The signs of slowed growth in some sectors suggest that the recovery may continue well into 1985 without the inflation symptomatic of a rapid recovery. Most of the slowdown in growth was absorbed by business inventories, personal consumption of durable goods, and residential fixed investment. Business inventories grew by only 68 percent as much as in the first quarter, personal consumption for durable goods grew by 58 percent of the first quarter rate, and residential fixed investment slowed to only 44 percent of the first quarter growth. Sectors with accelerated growth in the second quarter included personal consumption of nondurable goods and of services, which increased at annual rates of 9.6 percent and 3.8 percent, respectively, and Federal purchases of goods and services, which increased at an annual rate of 47.9 percent.

Jan 1, 1984

By J. Goyman, K. R. Rawling

"1.1 Location and Transportation ServicesNanisivik Mines Ltd. is located at latitude 73°, 3,200 km north of Montreal and 700 km north of the Arctic circle, on the south side of Strathcona Sound, which is an arm of Admiralty Inlet, in Northern Baffin Island. The orebody and mill site are 4 km distant from Strathcona Sound which provides deep water anchorage for ocean transportation of concentrate to Europe during the short northern shipping season from mid-July to mid-October.The operations and the resident community have direct jet aircraft service from Montreal two days per week, and local nights connect with other Arctic communities in the northern Baffin region. Bulk supplies and general cargo are delivered in the summer shipping season.1.2 HistoryThe Texas Gulf Sulphur Company, now Kidd Creek Mines Limited, staked claims in the Nanisivik area in 1957 and carried out exploration through to 1968. After the Kidd Creek orebody was found, Texas Gulf optioned the property in 1972 to Mineral Resources International Inc. (MRI), which undertook further exploration and completed a feasibility study.Nanisivik Mines Ltd. was formed in 1975, with MRI as the majority shareholder and minority shareholdings held by Metallgesellschaft, Billiton and Texas Gulf. Strathcona Mineral Services Limited was retained to manage the project during both the construction and operational phases."

Jan 1, 1984

By Jack O?Hearn

A liquid and solid waste management plan for an operating uranium ore processing mill was developed to efficiently and effectively dispose of existing solid wastes and related, affected surface and ground water resources. The goal of this management plan was to achieve satisfactory clean up of these existing wastes ad their by-products as well as to prevent similar situations from occurring in the future. An existing, modern system of synthetically lined tailings ponds, constructed after many years of mill operations, now provides an approved site for the disposal and containment of waste streams currently generated by the mill. This system was thought to be readily adaptable to serve as a key element of the waste management plan. The potential presence of extra capacity in these ponds could eliminate or reduce expenditures for new facilities required solely for proper management of liquid and solid wastes generated by operations prior to construction of the modern tailings ponds as well as for a range of anticipated future operations.

Jan 1, 1984

By M. J. Meulendyke

An extensive program of marked ball wear testing (MBWT), laboratory corrosion studies, and worn ball surface analyses has been used to gain insight about the role of corrosion in the overall wear process. In some environments, localized corrosion is observed; the actual wear mechanisms in such cases are pitting/spalling and abrasion. Factors affecting the occurrence of pitting include the abrasiveness of the ore, corrosivity of the slurry, corrosion resistance of the media, and galvanic coupling effects. Elimination of pitting substantially improves overall wear resistance. When pitting is not observed, the contributions of general corrosion are significantly less.

Jan 1, 1984

By Dirk van Zvl

The design of cover systems for reclamation schemes in tailings requires estimation or determination of tailings materials properties such as compressibility, shear strength and consolidation characteristics. It is very difficult and expensive to obtain truly undisturbed tailings samples for laboratory testing. In situ testing methods have been developed for economically obtaining large amounts of information. Two of these methods are described, the piezocone and the flat plate dilatometer. Both of these methods provide a rapid means of detailed material identification in a nearly continuous fashion for the entire depth investigated. The equipment is described and typical data from a uranium tailings impoundment is presented. The results are compared and the advantages and disadvantages of these methods are discussed.

Jan 1, 1984

By M. M. Tilman

The Bureau of Mines evaluated corrosion resistance of Split Set friction rock stabilizer mine roof bolts to aid in better prediction of useful service life. Electrochemical corrosion testing was conducted utilizing an automated corrosion measurement system. Natural and/or synthetic mine waters from four uranium and two copper mines were the test media for the two types of high-strength, low-alloy (HSLA) steels from which Split Set stabilizers are manufactured, and for galvanized steel. Tests were conducted with waters of minimum and maximum dissolved oxygen content at in-mine water temperatures. Retrieved Split Set stabilizers were also evaluated for property changes. Galvanized steel was found to be far superior to the unprotected steel in general corrosion resistance; limited tests indicate little ten.dency to pitting, contrary to behavior for the uncoated steel. Copper-bearing HSLA steel was slightly more corrosion resistant than non-copper-bearing HSLA steel. Statistical analyses resulted in development of equations relating dissolved oxygen, chloride, sulfate, and magnesium contents of mine waters to corrosion rates of the two HSLA steels (nongalvanized). An equation was developed that relates corrosion rates of galvanized steel to mine water temperature and dissolved oxygen content. Variable conditions in mine environments make corrosion damage difficult to predict and emphasize the need for corrosion prevention and control.

Jan 1, 1984

By D. Marcus

A methodology was developed wherein. the increase in compressive strength, mineralogical changes and pore water composition were all studied simultaneously as a function, of moisturized spent shale curing time. From these results the relationship between the nature of cementation process and the composition of pore water was established. Heavy metals were entrapped in the cementing constituents and the pore water became mainly a solution of alkaline sulfates. While the specific data are applicable only to the material studied, the methodology and general conclusions are useful for evaluating the environmental factors in spent shale disposal and expected leachates composition.

Jan 1, 1984

By W. F. Watts

This report describes a statistical analysis of 41,502 respirable quartz dust samples collected from 1974 through 1981 in metal and nonmetal mines and mills. The goal of this Bureau of Mines study was to identify commodities and occupations associated with high quartz dust exposure so that future enforcement and research activity can be focused on the high-exposure areas. For this analysis, the Bureau used its computerized Mine Inspection Data Analysis System (MIDAS), which contains data on nearly 350,000 air samples, including data for 61 contaminants in 45 commodities. The samples analyzed were collected by inspectors of the Mine Safety and Health Administration (MS HA). The data were entered into the MIDAS computer and coded according to commodity, occupation, location, and other categorical information. Occupations an. commodities with high quartz dust exposure were identified by grouping the data by code categories. Workers at sandstone, clay and shale, and miscellaneous nonmetallic mineral mills had the highest quartz dust exposures. Within these mills, occupations with high exposures were baggers, general laborers, and persons involved in crushing, grinding, and sizing operations. Dust concentrations in these mills were not necessarily the highest, but because the dust contained a high percentage of quartz, the health risk from dust exposure was the greatest.

Jan 1, 1984

By V. Balakrishnan, A. Hewitson

"The Kudremukh Iron Ore Company Limited, a government of India enterprise, has constructed iron ore mining, crushing, handling and concentrator facilities at Kudremukh, in southwest India. Concentrate produced is pumped 65 km to dewatering, storage and ship-loading facilities which were built at the same time at the sea port of Mangalore.A computer-based distributed process control system was implemented for all operations at Kudremukh and to interface with and monitor the Mangalore plant.The control system is examined from various standpoints, beginning with a description of its architecture, method of process input/output connection, and major hardware items.Software considerations and process applications are then looked at, with a review of the integration of the computer vendor's system software with user-developed applications programming. A control example of crusher operations is provided.Following the descriptive segment is a discussion of the design considerations and decision factors involved in the implementation of such a system considering the type of process and the remote nature of the installation site. It ends with a review of actual operating experience and conclusions regarding both this system and future similar applications.ScopeThe following is a discussion of the computer-based process control system applied for the Kudremukh Iron are Company Limited's ore handling, concentrating and shipping facilities located in South India.A general description of the process and plant equipment will be followed by an examination of the control system from the points of view of hardware and signal flow, software requirements, design considerations, implementation logistics and operating experience. Conclusions will be drawn concerning this and future computer applications."

Jan 1, 1984

By Michael K. Phang, Thomas A. Simpson

Field studies at an underground mine site were conducted to evaluate and monitor blast-induced vibrations on an underground coal mine roof. The vibration data were evaluated so that a suitable damage criteria or guidelines from which a safe operating distance between surface blasting and underground mine operations can be established.

Jan 1, 1984

Data released by the Commerce Department's Bureau of Economic Analysis show continued gradual change in the real GNP's rate of growth in 1984, which has eased from an annual growth rate of 10.1 percent in the first quarter lo 7.1 percent in the second quarter, and then to 2.7 percent in the third quarter. The automobile industry strike in the last half of September had only a small effect, estimated at less than a 0.1 percentage point reduction in the growth rate. Among the components that comprise the GNP, personal consumption and fixed investment grew at lower real rates in the third quarter than in the second quarter, while net exports decreased. Personal consumption expenditures increased $0.4 billion in the third quarter, compared with an increase of $20.1 billion in the second quarter. Nonresidential fixed investment increased $3.9 billion in the third quarter, compared with $9.6 billion in the second quarter. The other component of fixed investment--residential investment--increased from $60.8 billion in the second quarter to $61.2 billion in the third quarter. Real net exports of goods and services decreased $1 1.3 billion in the third quarter, compared with a $3.1 billion decrease in the second quarter. Although exports increased from an annual rate of $144.7 billion to $150.2 billion, imports increased much more, from an annual rate of $1 56.2. billion to $172.8 billion (table 1).

Jan 1, 1984

By James A. Kiger

We at Colowyo would like to thank you for the opportunity to share with the Society of Mining Engineers of A.I.M.E. the progress of reclamation at Colowyo Coal Company's multiple seam open pit coal mine which is a general partnership of W.R. Grace and Co., and the Hanna Mining Co. First, a brief history of Colowyo Coal Company (Colowyo). The Colowyo operation is located approximately 28 miles southwest of Craig, Colorado, which is in the northwest corner of the state. The Colowyo operation produces coal from a Federal Coal Lease, a portion of which has experienced previous coal mining by underground methods. The underground coal mines were known as the Red Wing Mine and The Streeter Mine, and supplied coal to numerous locations in the Rocky Mountain region.

Jan 1, 1984

By Stephen L. Bolivar

The Prairie Creek intrusion, near Murfreesboro, Arkansas, is the site of the only commercial diamond mine in North America. Three major lithologies are associated with the intrusion, a hypabyssal peridotite, a volcanic breccia in .which the majority of diamonds occur, and associated tuff. Previous studies, including mining history, geological, geophysical, petrological and whole-rock and mineral chemistry are reviewed. The recent suggestion, by other workers, that this intrusion may be more correctly called a lamproite is examined and supported. This has serious implications for diamond exploration in Arkansas and elsewhere in the U.S.

Jan 1, 1984

By S. Chander

A review of the published literature on the mechanism of depression of sulfide minerals shows that a unified theory is not yet available. The various mechanisms that have been postulated include competition between depressants and collectors to adsorb at the surface sites, creation of thermodynamic conditions nonconducive for formation of a metal collector salt or formation of a hydrophilic coating on the surface. The hydrophilic coating may or matt not effect the adsorption of collectors. In yet another mechanism, the depressant nay participate directly in oxidation/reduction reactions between collectors and sulfide minerals. Examples from the literature are discussed to highlight oxidation/reduction effects in the depression of sulfide minerals.

Jan 1, 1984

By Kevin Lofftus

The rest potentials of molybdenite electrodes are measured as a function of pH in absence and presence of flotation reagents. The chemicals used include sodium ethyl xanthate, kerosene, dextrin,sodium hydrosulfide, hydrated sodium molybdate, sodium sulfate, and hydrated sodium thiosulfate. The effect of dissolved oxygen is also noted. The obtained data are correlated with the results of micro-flotation tests obtained under similar chemical conditions.

Jan 1, 1984

By Terry R. Guilinger

A minitest of the new potassium chloride-potassium carbonate two-stage in situ uranium leach process has been carried out at the Intercontinental Energy Corporation (IEC) Zamzow project site in South Texas. Substantial quantities of high concentration uranium were produced indicating the viability of the leach solution. The test results yield information regarding the reservoir dispersivity, the average cation-exchange capacity of the formation, and the distribution coefficients describing carion-exchange reactions. The test a1 so indicates permeability anisotropy and the existence of disturbed flow fields. The research was partially funded by the U.S. Bureau of Mines.

Jan 1, 1984

By Noakes MJ, Willsteed TV

In the past few years an elevated gold price has resulted in the evaluation of many small scale surface gold deposits in Australia typically containing about 2-3 g/t Au. Operators have tended to assume that at the lower end of the grade spectrum only heap leaching is economically possible whereas above some assumed "cut-off" grade, carbon-in-pulp or similar techniques can be considered to have economic advantages.Studies made on a number of these prospects has indicated that this rather arbitary choice of treatment method can be mis-leading.A case study has been prepared assuming a "typical" situation and is presented. The deposit contains three million tonnes of ore assaying 3 g/t Au and is amenable to open pit mining methods. The mine site is remote but accessable and existing infrastructure is minimal. There are no unusual environmental constraints.

Jan 1, 1984

By Joseph W. Leonard

Much progress has been made in the application of geostatistics to hard rock ore deposits.1,2,3 4,8 Progress in the application of geostatistics to coal deposits has developed over a period of time out of hard rock technology.5,7 Exploratory drilling in many hard rock deposits is frequently significantly more productive than exploratory drilling in coal deposits. For example, hundreds of feet of drilling and/or many drill setups are frequently necessary to obtain a few samples from a typical 4 to 6 foot thick coal seam. With hard rock deposits, which are frequently thick or volumetric, less drilling dead work is involved in sampling the deposit. To produce a variogram, which is the basic element needed for geostatistical analysis, a few well positioned holes drilled into a hard rock deposit where the core(s) can be divided into many sections can produce a detailed variogram. To produce a similar type variogram in coal, it is necessary to drill many dozens of holes with much of the core length consisting of overburden data which is frequently of only secondary importance. To apply geostatistics to coal, not only are many separate sample sites needed, but frequently a problem exists in that the interval distance between samples cannot be controlled with the ease that hard rock drilling intervals can be controlled where it is only necessary to cut core segments according to some preassigned interval of distance. Because the uses of existing coal deposit samples are frequently handicapped by irregular sample distances and lack of sampling density along certain directions needed for the development of variograms, the application of geostatistics to coal deposits frequently does not proceed with the same efficiency and rapidity as when these techniques are applied to ore deposits. Grid-fitting was developed by the writers, as a logical and evolutionary improvement over the long and successful application of geostatistics to coal seams.6,9 Grid-fitting combines the trending of variance as well as other aspects of probability theory to optimize informational yields from the commonly less productive data derived from coal exploratory programs. Grid-fitting is basically a technique where a hypothesis involving numerous grid patterns, where each pattern is of a given geometry, size and direction is repeatedly matched against actual sample data to determine which match results in the closest fit of the hypothesis to the data. To determine the closest fit, a special index known as a selectivity index was developed. The selectivity index is basically the product of the mean and variance of the variances contained within each of the grids. hence, if SI is the selectivity index then [SI = Xs E (S i - Xs) /N] where [X]s is the mean of individual grid variances Si2 for any pattern of given geometry, direction and size.

Jan 1, 1984

By T. Piirainen, T. Alapieti

"The Koillismaa layered igneous complex is the result of igneous activity that occurred 2436±5 m.y. ago. Its crystallization took place in three separate but connected magma chambers, the total volume of which is estimated at more than 2000 km'. These chambers were located partly in a feeder system within Archaean granitoids and partly in an unconformity between these grani­ toids and Early Proterozoic supracrustal rocks. The composition of the parental magma that initially filled the chambers is thought to have been that of a relatively MgO-rich tholeiite. Sulphides and platinum-group minerals are mainly concentrated in the marginal series of the western part, where they are encountered over a distance of 25 km. This marginal series is an originally nearly horizontal series of rock types that displays a reversed differentiation trend, grading inwards from gabbroic to ultramafic rocks, followed bv rocks of the layered series. The chilled margin is not encountered anywhere in its original position at the contact, probably as a consequence of magmatic erosion, but remnants are to be found in the form of elongated xenoliths. Partly melted siliceous fragments from gneissic country rock typical of the lower part of the marginal series indicate pronounced contamination.Chalcopyrite, pentlandite and pyrrhotite±pyrite are the predominant sulphides. The accessory sulphide minerals include covellite, violarite, marcasite, mackinawite, sphalerite and argentian pentlandite. Platinum-group minerals are represented by froodite, michenerite, merenskyite and sperrylite. Other accessories that have been identified are electrum and native copper and gold. The mean of the Cu/(Cu+Ni) ratio in the mineralizations is 0.67 and Pt/(Pt+Pd) 0.31.It is suggested that the sulphide phase was formed in the marginal series as the solubility of sulphur in the basic magma was lowered by contamination, possibly assisted by some other factors. The sulphur isotope data support the juvenile origin of the sulphur."

Jan 1, 1984

By L. E. Schultze

The Bureau of Mines has devised techniques to recover lithium from geothermal brines as the chloride. More than 99 pct of the lithium was precipitated from a brine containing 170 mg/L Li by adding a solution of AICl3 and increasing the pH to 7.5 with lime slurry. The Li-Al precipitate was dissolved in HCl and sparged with gaseous HCI to recover the AlCl3; this resulted in a solution containing LiCl and CaCI2. The solution was evaporated at 1000 C to obtain a mixture of the chlorides from which 97 pct of the lithium was recovered and 90 pct of the calcium was rejected by leaching with tetrahydrofuran. The LiCl recovered by evaporation of the tetrahydrofuran was purified by dissolution in water and treatment with oxalic acid. The final LiCl solution contained 89 pct of the lithium originally present in the brine and had a purity of 99.9 pet.

Jan 1, 1984