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By Richard A. Hunnisett

Silica sand is one of the world's most plentiful resources and is a basic necessity in our way of life. The end uses of silica sand are an integral part of our homes, transportation, and places of work. The environmental legislation enacted in the early 1970's, coupled with the oil embargo and higher than normal inflation, have had a very real impact on the industry and its primary consumers, the foundries and glass producers. The present environmental laws directed at air and water pollution and the working environment can, in most cases, be met, but not without large capital expenditures for equipment. These expenditures must reduce the funds available for expansion and modernization of existing processes which are necessary if the costs to produce industrial sand are to remain at acceptable levels. The concern for the future is the enactment of more stringent laws, and the available technology and equipment to economically comply with them.

Jan 1, 1978

By Woodcock J. T

A sulphide ion selective electrode (ISE) is suitable for control of sodium sulphide additions in flotation because it has a rapid response to changeS in S2- concentrations, can indicate -low concentrations at differentpH values, suffers from few interferences, and is robust enou'gh to use in a pulp. Three sulphidization techniques were studied using the lSE electrode for measurement and/or control of S2- levels. Metallurgy was assessedfrom concentrate grades and copper recovery.With slug additions of sodium sulphide, sulphidizing conditions were poorly defined and reproducibility tended to be poor. Although acceptable metallurgy could be achieved by multiple additions, sodium sulphide consumption was high.Controlled potential sulphidization readily gave good metallurgy. The optimum potential of the lSE for sulphidizing was about -500 mV versus SCE, but depended on sulphidization and flotation times; suitable times were3 and 5 min respectively for three to five stages. Application of this technique to previously untested ores gave good metallurgy in a first test in spite of variation by a factor of three in the sodium sulphide requirements ofthe ores.Simultaneous sulphidization and flotation was satisfactory when conducted at an lSE potential of -450 mV versus SCE. Mixed cha!copyrite-oxide copper ores responded satisfactorily.Besides optimizing sulphidization conditions it is also necessary to optimize xanthate additions (e.g. by measuring xanthate residuals).

Jan 1, 1978

The recommissioning of the plant at Mary Kathleen involved several distinct phases. The previous plant process was modified significantly, the plant capacity was increased by the addition of new equipment and the exist- ing equipment was in most cases overhauled. This equipment was either reused in its original duty or relocated. Maintenance requirements after the plant was cmommissioned were high because of the amount of modified equipment and also because some old items of equipment were deliberately not overhauled during recommissioning. The equipment that was overhauled has operated reliably. However some new equipment has not been as satisfactory.

Jan 1, 1978

By M. Dayne Aldridge

A discussion of the definition of automation in mine ventilation applications is presented. The results of theoretical studies, experiments and practical experience from work in the United Kingdom, Belgium, Poland, the Soviet Union and the United States are summarized. Conclusions are drawn from these efforts and the prospects for the future development of automatic mine ventilation systems are explored.

Jan 1, 1978

By K. Voltaire

As can be guessed from the subtitle, this paper will not be a geologist's one since neither of the authors is a professional geologist. This will be an attempt to present the various aspects of the legal, economic and geological setting that condition the exploration for mineral resources in Haiti. Before going any further, we are going to present a summary of our rather short mining history. One must first mention that Caribbean countries are latecomers to the mining business. If we go back to the colonial period (1500-1600's) there are net many traces of mining activity. The major exception to this is the recovery of alluvial gold in Hispaniola, Puerto-Rico and Cuba and also some sporadic copper mining in Hispaniola (notably in Haiti near the city of Gonaives and in some of the old mining districts in Santo-Domingo). These easily minable deposits were quickly exhausted and mining quite naturally came to an end as agriculture rose as the major economic activity. In the Haitian case, aside from very erratic mention during the 19th Century of the presence of some minerals (i.e. haematite, chalcopyrite) no serious geological work was undertaken. In the meantime, the peasants in the northern part were still looking for alluvial gold in some streams but this amounted to next to nothing. One has to come to the 1920's to find the first comprehensive geological survey. At the time, the country was under the military control of the United States. The American Government sent a team from the U.S.G.S. headed by the late W. Woodring to initiate a survey of the country. Given the lack of transportation, this was a tough task and Woodring and his associates did it magnificently. As a result of their efforts, they published a very thick piece of work of more than 600 pages. "The Geology of the Republic of Haiti" although it was published in 1924 is a classic and is a must for anyone interested in the geology of Haiti.

Jan 1, 1978

By Roach C

Exploration on the Callide Coalfield by Thiess Bros. Pty. Limited had reached the stage in mid 1976 where there was a need for a comprehensive appraisal of the coalfield geology. Exploration strategy in 1977 - 1978 was defined by the selection of the most attractive targets. All available literature, reports and plans were reviewed and borehole records assessed. The geology of the coalfield was placed in its regional setting and the genesis of the Callide Coal Measures described in a structural and sedimentological context. Their general form and extent was then examined by the technique of stratigraphic analysis through the interpolation and extrapolation of the available data. A "localized" reserve classification was drawn up and reasonable estimates of the various geological reserves produced, in terms of their reliability and depth of overburden. Quality trend maps were also produced. The resultant "base map" was virtually a summation of all the information to June, 1977, and the basis for the exploration programme in the 1977 - 1978 financial year. The technique allowed for "base maps" to be produced at almost any stage, each one a refinement of its Predecessor.

Jan 1, 1978

By A. F. Colombo

In an effort to maintain an adequate supply of iron to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, is conducting research on methods for beneficiating the oxidized taconite resources located on the western Mesabi range in Minnesota, thus expanding domestic iron ore reserves. The selective flocculation and cationic flotation process was investigated in a pilot plant using an ore feed rate of 410 kg/hr (900 1b/hr) and 88 percent recycled water. Lime and a cationic flocculant were used to clarify the waste slurries treated in the water reclamation circuit. An oxidized taconite assaying approximately 36 percent Fe yielded concentrates averaging 63.5 percent Fe and 4.3 percent SiO2 and having an average iron recovery of 84.4 percent. The estimated reagent cost per tonne of concentrate was approximately $1.10. In an attempt to recover more of the iron lost in the flotation tailing, wet high-intensity magnetic (WHIM) separation was incorporated in the pilot plant circuit. The flotation concentrate grades obtained from beneficiation circuits with and without WHIM scavenging were similar, but when WHIM separation was used the overall iron recovery was increased by 2 to 9.5 percent, depending on the iron assay of the flotation tailing.

Jan 1, 1978

By L. R. Gremillion

Chemical and mineralogical data on 25 apatitic phosphate ores of diverse origins from commercial deposits around the world were widely variable. From 14 to 18 chemical constituents of each sample were determined, and each sample contained 4 to 10 mineral phases. Altogether there were 34 different mineral phases, many of which occurred in only one sample. The samples contained varieties of francolites, fluorapatites, and mixed hydroxyl-fluorapatites. The apatite compositions calculated from the chemical data showed that certain types of substitutions were characteristic of different apatite varieties, but every variety had some degree of substitution of (CO3)2 for (PO4)3 and the P2O5 contents of the apatites ranged from 35.1% for a North Carolina apatite to 41.9% for a Missouri apatite. In a concentrate with a grade of 32% P2O5, the North Carolina sample should contain about 8.7% gangue and the Missouri sample about 23.7% gangue. To optimize the digestion process of a phosphate are, it is necessary to consider the dissolution behavior of the different mineral phases during acidulation and the effects they may have on the chemical properties of a fertilizer intermediate. In the production of wet-process acids or superphosphates, the acidulation of certain minerals may cause foaming and formation of sludge, filtration, corrosion, and handling problems.

Jan 1, 1978

By Ronald L. Wiegel

In a mineral processing plant there are a number of routine decisions which are based at least in part on the plant's metallurgical performance. Among these are those related to: 1) equipment functioning properly 2) suitable operating conditions 3) reagents achieving desired results 4} determining operating response to changes in ore 5) defining circuits offering potential for improvement A step beyond the routine, are the periodic management evaluations of operating supervision and technical assistance, which are based largely on profit -a direct function of are availability, metallurgical performance and operating costs. The "yardstick", excuse me -"meterstick", by which performance is best measured is the plant metallurgical balance, which tells not only what was produced but how it was produced. Since this metallurgical balance is directly related to both plant profits and individual rewards, it is only reasonable to make that "meterstick" as precise as humanly possible.

Jan 1, 1978

By D. Montagna

This Bureau of Mines report describes a salt-free, fluxless method for reclaiming metallic aluminum from aluminum dross. The dross is smelted under argon, nitrogen, or carbon dioxide, instead of a salt flux, in an externally heated pot furnace. Aluminum recovery, using argon, is equal to recoveries reported from commercial smelters that process dross in rotary-type furnaces This salt-free method could offer a reduction in air pollution, lower energy requirements by elimination of salts, and the production of up to 60 percent less solid waste for disposal than the salt method.

Jan 1, 1978

By James R. Aggson

This paper summarizes the research effort that was conducted as part of a cooperative agreement between the U.S. Bureau of Mines, Denver Mining Research Center and the Pittston Company. The objective of this investigation was to further the understanding of the floor heave ground control problems that have plagued underground mining of the Beckley coalbed in southern West Virginia. Floor heave is both economically and structurally undesirable. Floor heave is accompanied by a redistribution of stresses and loads that are associated with an underground opening. This redistribution of stresses may cause roof or pillar problems that otherwise would not have occurred. The floor heave that occurs in the Beckley coalbed is not cons1dered to be caused by "squeezing" or plastic flow of the materials involved. The "squeezing" type floor heave is normally associated with relatively weak floor members that contain significant amounts of clay mineralization. The floor members in the Beckley coalbed are competent, relatively strong materials which fail in a manner that can best be described by the term "buckling." This buckling-type failure is indirectly related to the time-dependent deformation properties of the materials involved, but is considered to be more of a slender column, or panel, type failure than a "squeeze" or "flow"-related failure. The Beckley coalbed has had a history of floor heave ground control problems. The Glen Rogers mine, which opened in the 1920's, experienced extensive floor heave. In a report dated April 1929, James P. Keatley of the West Virginia State Department of Mines described the floor heave in the Glen Rogers mine. Several observations listed in the Glen Rogers report that appear to be consistent with current observations follow: 1. Water plays no apparent part in the floor heave process. 2. No evidence of gas has been found in the floor. 3. The thickness of the overburden, which varies from 183 to 396 m (600 to 1300 ft), has no relationship to the floor heave. In the conclusions of the 1929 report on the Glen Rogers mine, Keatley states, "A statement in brief as to the cause (of floor heave) would lie that an undetermined natural condition doubtless augmented by former and present mining methods causes the bottom to heave." As this report will show, Mr. Keatley's insight into the problem was most accurate. The "undetermined natural condition" is the existence of a biaxial, horizontal, compressive stress field. This stress field is in excess of that which would be expected from gravity loading. This stress field and the material properties of the floor rock combine to cause the floor heave that has been experienced. The floor heave that occurs in the Beckley seam generally occurs as arching, with a tension fracture, near the center of the floor span or as a break near the rib followed by vertical deflection (of the floor) at the rib and sloping of the floor across the entry. Examples of the floor heave are shown in Figures 1 and 2. The two types of floor heave are merely different manifestations of the same basic failure mechanism. When the entries experiencing floor heave were identified on a map of the mine under investigation, it was apparent that there was a relationship between the floor heave and the direction of the entries. The main entries, which are used for ventilation and haulage, experienced the majority of the floor heave. This directional relationship suggested a directionally related loading mechanism, or more specifically, a biaxial, horizontal stress field that exceeds what would be expected by gravity loading. Since the main entries were oriented at a bearing of N25oW, it was hypothesized that the maximum compressive component of the horizontal stress field was at 90° to these entries or at a bearing of N65oE. An in Situ testing program was developed to test this hypothesis and investigate the floor heave problem.

Jan 1, 1978

By R. A. Hill, J. D. Pitts

"Long distance slurry pipeline systems have been successfully trans-porting steam coal, iron concentrates, copper concentrates and limestone for an aggregate of nearly 60 years and nearly three billion ton-miles annually. A phosphate concentrate pipeline is nearing start-up and systems for coking coal, lead/zinc concentrates and fly ash are planned. The solids pipeline concept, first patented in the early 1900's and commercialized in the 1950's, is now a proven technology providing an economic, environmentally pleasing and safe method for long distance bulk transport.The challenge for larger tonnage and longer distance movements of solids, for traversing increasingly rugged terrain in grass roots mineral developments, for transporting untried materials and for shipping more economic forms of proven materials still remains. This has necessitated continued refinements and optimization of the technology. The economic and environmental incentives for slurry pipelines when compared to other transport alternatives has justified substantial activity in this area. The scope of planned systems in coal, iron and other minerals is indicative of the firm place slurry pipelines will have in worldwide mineral development.In this presentation, the state-of-the-art in long distance slurry pipelines is reviewed with a focus on major systems of interest to the mineral processing industry. An overview of new developments in the application of this concept is presented, and finally, a projection of the future of pipelines in mineral development both worldwide and in Canada is discussed."

Jan 1, 1978

By I. Yaniv

The magneto-hydrostatic method can be used today to separate slightly magnetic or non-magnetic particles according to differences in their specific gravities and magnetic susceptibilities. The classical approach is to effect stratification prior to separation. This paper discusses some of the significant parameters which bear on the design and pattern of the expected stratification in the separation cell. As the characteristics of the magnetic field, and consequently those of the magnetic forces, are determined by the geometry of the poles, this subject is treated first. In this context a new approach, whereby the range of stratification is extended, using positive as well as negative gradients, is presented. Finally, the effect of the relative size and shape of the particles on stratification is discussed.

Jan 1, 1978

By Daryl R. Tweeton

Bureau of Mines research in in situ uranium leaching includes injection well construction and environmental aspects. Clogging of injection wells is a common problem, and is affected by construction techniques. Part of the clogging can be caused by a low-permeability skin left on the borehole wall if the drilling fluids are not thoroughly flushed out. Certain polymer drilling fluids are less prone to cause clogging than bentonite muds, since a lower solids content can be used. The environmental research primarily involves two contracts. The first describes the environmental impact of in situ leaching and the effect of environmental legislation on leaching; the second describes the cost effectiveness of various methods of restoring ground water quality.

Jan 1, 1978

By Howard E. Mitchell

Modern mechanical raise drilling was first introduced into the United states in 1962. This method of safely, economically raising a shaft has steadily increased in popularity since that time. This steady growth has been largely enhanced by the many advantages to be gained by mechanical raise drilling, as well as by the increasing reliability of the equipment required. It is the purpose of this paper to briefly review the state of the art of raise drilling to include: the various applications and advantages; the equipment requirements, including a comparison of the various types and sizes of machines and rock cutting equipment; equipment performance; and future trends.

Jan 1, 1978

By Jr. Smith

Silver-gold ratios were studied at the Tayoltita epithermal vein deposit using channel sample, channel sample line, stope, ore body and vein sample populations. The ratios are highly variable among individual channel samples (25:1 to greater than 500:1) with both high and low values randomly distributed within ore bodies and veins. Whole vein ratios for the fourteen most important ore producing structures range from 44:1 to 105:1, and show zonal distribution relative to two small granitic stocks, low values closest to the intrusives. The zoned nature of the deposit suggests that the stocks, apophyses of an underlying batholith of Late Eocene age, were the heat engines which powered the hydrothermal system responsible for ore deposition.

Jan 1, 1978

By D. S. Davies

Further development of the Nitric-Sulfuric Leach (NSL) process has led to an improved design of the leach and nitric acid recovery steps. NO produced in the leach step is reacted with oxygen, regenerating N02, which is sparged directly into the leach reactor. Leaching is simplified to two steps and the nitric acid plant is replaced with an oxidation recycle gas sys-tem. Laboratory work substantiated the concept and led to selection of operating conditions. The lab work also pointed to improved process control compared to use of nitric acid as the sole oxidant. Recovery of copper from purified pregnant liquor is modified to use air agitation electrowinning improving cathode quality and lowering tankhouse costs. Economic evaluation shows reduction of capital requirements from $2400/AT to $2000/AT in 1978 dollars for 50,000 TPY of copper production.

Jan 1, 1978

By J. Philip Bromberg

The 1977 Clean Air Act Amendments will have a large effect on the coal-fired segment of the electric utility industry. Since electric power generation constitutes by far the largest single use for coal, this legislation has the potential to greatly affect future patterns of coal utilization in the U.S.A. The inability to depend exclusively upon low sulfur coal as an exclusive mode of compliance with New Source Performance Standards may greatly lessen projected demands for low sulfur coal by eastern utility boilers. The requirements of the legislation is discussed with particular reference to the needs of the electric generating industry, along with the technologies available for complying with the Act.

Jan 1, 1978

By H. Kenneth Sacks

The Bureau of Mines has developed hardware for electromagnetic (EM) detection and location of miners trapped in underground coal mines. This report describes a technique for using the developed equipment for locating uncased boreholes underground. Results of several field and laboratory experiments are described.

Jan 1, 1978

By J. A. Clum, R. W. Heins, T. D. Tiemann

The use of Na-montmorillonite clay binders (Western Bentonite) in the pelletizing of iron ore concentrates is well established as is the idea that alternative binders must be found. 1-6 This note summarizes work done7 in evaluating a Wisconsin montmorillonite clay binder. The clay occurs in irregualr beds overlying the Prairie du Chien Dolomite and the St. Peters Sandstone near Hersey, St. Croix County.

Jan 1, 1978