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By Edward M. Kawenski

Float dust deposits in return airways in bituminous coal and lignite mines present a special explosion hazard. Research is in progress at the Bureau of Mines experimental coal mine to evaluate the degree of the hazard and to develop measures for preventing dissemination of dust into the ventilating air current. To determine the extent of this hazard prevailing in operating coal mines, 711 dust samples were collected in 50 mines located in the major coal fields of the United States. The mean quantity of coal and the incombustible content of the dust in the samples were determined. The term "float dust" is used to designate particles smaller than 74 microns in diameter (particles passing a No. 200 sieve) which have settled from the air current. Dust usually found in roadways and in working places is coarser than float dust, and is termed "coarse dust" (particles passing a No. 20 sieve). Variations in amount and incombustible content of coarse dust in a midwestern mine were studied previously.

Jan 1, 1963

Difficulties were experienced in the identification of carbonate minerals intimately associated with iron oxides in the so called carbonate ore, which occurs at depth in the Iron Duke Orebody.Determination of refractive indices by examination under the microscope using the immersion method, together with inferred chemical composition indicates that dolomite and parankerite are common constituents. Histograms of the manganese and sulphur contents strongly suggest that manganese is associated with the carbonate minerals, and that the highest sulphur assays occur near the base of the carbonate body.From the present work it is concluded that refractive indices indicate only a very approximate composition for carbonates of the parankerite type.The different carbonate minerals occur in irregular zones.INTRODUCTIONThe Iron Duke deposit is situated in the southern portion of the South Middleback Range on Eyre Peninsula, S.A., 30 miles from Whyalla. (Fig. 1).Drilling at Iron Duke revealed a large body of so called carbonate ore, which was tested in detail at cross section 1000 ft. S by three diamond drill holes, DDH.57, 67 and 78. (Fig. 2)Most specimens of carbonate ore described below were obtained from DDH 67 and 78.GENERAL GEOLOGYThe South Middleback Range is composed of two parallel ridges trending north-south. The Iron Duke orebody is situated on the southern portion of the western ridge. (Fig.1) .The rocks of these ranges belong to the Middleback Group which rests on a gneiss complex. Their age is considered to be Middle Precambrian or late Archaean.

Jan 1, 1963

By James S. Browning

Recovery of fine mica from a sample of impounded tailing from the Dixie Mines, Inc., crushing and screening operations, Heflin, Ala., was investigated to determine if plant losses of mica could be reduced while econmically producing a commercially acceptable mica concentrate. Conventional wet-tabling and agglomerate-tabling methods yielded concentrates assaying about 95 percent mica from the tailing that contained 17 percent mica. Products containing about 98 percent mica and accounting for mica recoveries of 86 percent were obtained by flotation, using as reagents sulfuric acid, kerosene, and coco amine acetate (a mixture consisting chiefly of dodecyl and tetradecyl amine acetates). The results of the batch flotation tests were verified by tests in a small continuous flotation pilot plant.

Jan 1, 1963

By John Nunes, Frank R. Larson

Temperature-dependent functions of various ten-sile flour stress and fracture parameters were investigated on iron and low composition alloys of Fe-C, Fe-Cr, Fe-Mn, and Fe-Ni. Data were obtained over a range of test temperatures from 200" to -196"C at an initial strain rate of 0.01 min". It was found that the strain-hardening exponent, n, for the Fe-Ni alloys increased significantly at very low testing temperatures with increased alloy addition. Also, the stress and strain at fracture followed a predictable transitional type of behavior. The flour stress-temperature dependence was evaluated employing the relation: M where it is shown that composition can strongly influence the constant M. An empirical formula describing this effect is as follows: M = MI (equivalent at. pct Ni)-'" Some preliminay, tests were run on several commercial steels to test the generality of this relationship. One of the phenomenological explanations of the ductile-to-brittle transition encountered in bcc metals is based upon the difference in the temperature dependence of the flow and fracture stresses.' It states simply that the fracture stress is relatively insensitive to temperature and that the yield or flow stress rises rapidly with decreasing temperature so that, when the flow stress reaches the fracture stress, brittle fracture occurs without appreciable plastic deformation. This behavior is illustrated schematically in Fig. 1 where the ductile-to-brittle transition is shown to occur at two possible temperatures. The lowest temperature, TB, represents essentially completely brittle behavior while the higher temperature, TN, represents "notch" brittle behavior. Support for this theory is obtained when it is observed that fcc metals, which do not commonly have a ductile-to-brittle transition, also do not commonly exhibit any strong temperature de- pendence of the yield stress. This relationship of yield or flow stress behavior with the ductile-to-brittle transition has been generally observed for most metals representative of these two crystallo-graphic structures. One exception to this generalization appears in the case of tantalum where no apparent ductile-to-brittle transition has been observed. However, this may simply be an indication that this type of behavior is not directly related to the flow stress and that some other mechanism such as twinning must also be operative. A comparison of the typical temperature dependence of the yield stress of some representative metals is shown in Fig. 2. In the study of the temperature dependence of the strength of metallic materials, considerable ef-

Jan 1, 1963

By A. J. Paul Laprairie

The process for which it is to be used is too often the only consideration in the design of a vessel. A de-sign allowing for practical manufacture and erection, as well as for proper maintenance, can often give over-all economies. Most platework in-stalled today is of welded construction. Therefore, metallurgical control is important in its manufacture. Also, because many concentrating and re-fining processes tend to be corrosive, the subject of protective coatings as a part of the manufacturing process is extremely important. The plant de-signer should know how to evaluate and specify controls for the metallurgy and for the coatings. Mining operations are becoming more sophisticated in the field of mechanical engineering. More and more emphasis is being given to preventive maintenance. The first step in any maintenance program, however, is good inspection service. This paper will suggest methods for the inspection of platework, and outline methods for repair and replacement.

Jan 1, 1963

Polyacrylamide flocculating agent has been used in the Leaching Division 'of the Risdon Works of the Electrolytic Zinc Company of Australasia Limited since October, 1960. The number of thickeners in the continuous thickening stage was thereby reduced from eight to three. There has been an increase of 25 per cent in throughput and a reduction of solids in thickener over-flow from 3-4 g/l. solids to 0·5 g Ir. solids. Reagent addition has been at the rate of 0·25 lb Separan NP10 per ton solids.Additionally there has been a gain of 3 per cent in current efficiency as the direct result of the addition of Separan NP10 to purified cadmium sulphate solution priOl; to electrolysis for cadmium metal. A smoother deposit has resulted and it has been possible to increase deposition time between strippings from 47 to 71 hr. However, there has been a slight increase in the lead content of the cadmium metal produced.The use of Separan NP10 to settle copper bearing residue in a batch process stage has resulted in a five-fold increase in settlement rate and a reduction in purification cycle time.INTRODUCTIONThe Electrolytic Zinc Company of Australasia Limited, Risdon, Tasmania, produces zinc by electrolysis of purified zinc sulphate solution, the raw material being zinc sulphide concentrate. In the Risdon process (Van Arsdale, 1953; J ohnstone, 1953; Ross, 1949) the compound zinc ferrite (ZnO.Fe203) is formed during the concentrate roasting stage. When the roasted material is leached in dilute sulphuric acid the zinc ferrite is not attacked, and it remains as part of the insoluble leach residue, of which it may form as much as two-thirds of the whole. The remainder is mainly unroasted zinc sulphide, unleached zinc oxide, lead sulphate, gypsum, silver compounds etc. The zinc in the residue may be 10 per cent of that in the original concentrate.Continuous thickeners are used to recover the valuable residue from the impure zinc sulphate solution and the...

Jan 1, 1963

An experimental study of the soil mechanics of brown coal showed that brown coal consolidates in the same manner as does a clay and that the theory of consolidation for soils may be applied to brown coals. Moisture content is a function of the coal type, the existing effective stress, and the stress history of the coal.The effective stress in a brown coal seam is a function of the overburden pressure, the pore stress and tectonic stresses. Stress history may be deduced from geological evidence and determined by consolidation tests. Application of these principles to the brown coal seams of the Latrobe Valley shows that the distributions of natural moisture contents are consistent with consolidation.INTRODUCTIONThe nature and geology of the brown coals of Victoria, particularly of the Latrobe Valley, were discussed in some detail by Edwards (1945, 1948), Thomas and Baragwanath (1949) and Gloe (1960). A salient feature of these studies was the distribution of moisture contents in the brown coal seams. Recent experimental work, part of a soil mechanics study of the structure and strength of brown coal, showed that moisture content variation is a reflection of consolidation phenomena in brown coal and application of the results to .field condItions verified and modified the conclusions of Edwards in his pioneer work. Further detail of this experimental work is recorded elsewhere (Rosengren, 1961).EFFECTIVE STRESS AND CONSOLIDATIONEffective stresses in soilsA saturated soil is a two-phase system, consisting of a compressible skeleton of rigid soil particles and pores filled with water, an incompressible fluid. (In this context, the terms compressible, incompressible, and rigid are relative only and refer to orders of magnitude). If this system is subjected to stress we define...

Jan 1, 1963

By Floyd G. Anderson

A study was made of the effectiveness of dust-control methods being employed in connection with continuous-mining operations. Airborne dust exposures of workmen and dust loadings of return air were determined for six types of continuous-mining machines. The conditions required for control of dust exposure are summarized and include ventilation of the working face by an exhaust system. Return-air dust loadings ranging up to 13 pounds per hour are reported.

Jan 1, 1963

By C. C. Harris, A. Jowett, S. K. Ghosh

An equation derived from first-order kinetics and accounting for return from froth to pulp has correlated continuous flotation data. The concentration of floatable material in the pulp can be altered either by changing the feed concentration or the feed rate. The latter does not affect the flotation rate constant, the froth to pulp return constant, and the concentration of non-floatable material in both the pulp and concentrate. Both the return constant and the concentration of non-floatable material in the pulp are directly proportional to the feed concentration, while the concentration of non-floatable material in the concentrate is related to the feed concentration. The investigation of the froth flotation process by continuous test methods, previously used by Brown and smith,1 Jowett and Safvi2 and Jowett and West,3 is being continued. Recent tests, primarily concerned with flotation cell design, have yielded kinetic data suitable for testing an equation proposed by Arbiter and Harris4 which postulates that a flotation process is defined by two rate constants: 1) the rate constant for mass transfer from pulp to froth. Previous workers have regarded this as the flotation rate constant. 2) the rate constant for mass transfer from froth to pulp, which has previously been ignored. THEORY Under continuous flow conditions at the steady state in Fig. 1 the equation developed4 is Symbols are defined in Table I. The air-liquid ratio terms4 have been omitted, since they are substantially constant for a given set of conditions. Also, for a system operating at the steady state Vf and V, remain constant and Eq. 1 can be written: Cp/Cc=b'/a,+Qc/a' [2]

Jan 1, 1963

By Hillary W. St. Clair

This is an initial progress report on a theoretical study of the iron blast furnace. The purpose is to develop a thermochemical model that will simulate mathematically a real furnace. An analysis is made of the behavior of a hypothetical furnace, operating adiabatically on pure ferric oxide, graphitic carbon, and dry air. Relationships are derived for carbon consumption, gas composition, and reaction temperature for a furnace operating at steady state, and in which the smelting rate is slow enough for the gas and solids to approach thermal and chemical equilibrium. Analyses are made for two contrasting types of gas flow: (1) Nonturbulent flow, having no vertical mixing; and (2) turbulent flow, having perfect mixing during each step of the process. It is shown that some vertical mixing is essential for complete reduction of ferrous oxide and that the extent of vertical mixing is one of the critical factors in the behavior of the furnace, This analysis indicates that the thermochemical relationships in a blast furnace can probably be best simulated by a finite series of gas-solid reactors through which gas and solids flow countercurrently and in which the temperature and composition of gases and solids are assumed to be uniform. Any degree of vertical mixing can be approximated by the proper choice of the number of reactors.

Jan 1, 1963

By L. G. Marshall

This report presents a cross section of the sand and gravel operations in the Minneapolis-St. Paul area. The study covers individual operations, economic problems peculiar to the industry, glacial geology of the area and its effect upon the grades and types of products, and past, present, and future trends of the expanding population and its effect upon the industry.

Jan 1, 1963

Geochemical data on Australian granites and pegmatites, and the mineral components of these rocks, are compared with that obtained in similar studies in the U.S.S.R. and elsewhere.The geochemical character of tin granites and the trace chemistry of their component minerals, particularly biotites, have some significance as ore guides in prospecting for tin.The primary geochemical dispersion of tin can be readily tested both in the laboratory and field by colourimetric methods, after volatilization with ammonium iodide, using modifications of the method described by Wood (1958).Secondary dispersions of tin in residual soils or alluvia can likewise be readly tested by rapid colourimetric methods in the field, but simple hydraulic methods, handling larger sample volumes, give reliable outlines of dispersion patterns.INTRODUCTIONThe search for tin ores, whether lode or placer in type, is usually directed on genetic grounds to country within or adjoining acid intrusives.A long established means of prospecting is to test samples for cassiterite by panning or other hydraulic separation.These methods can be used on crushed lode material or the natural materials from placers.With the advent of new techniques for extraction and for colourimetric analysis for tin (Wood, 1958 and Ross and White, 1961) a means is available for rapid analysis of materials not susceptible to quantitative testing by hydraulic methods because of the fine sizings of cassiterite or the occurrence of tin structurally held in minerals. The new methods thus opened up the field of tin prospecting by extending the search for ore guides to genetically associated rocks and minerals, wall ror-ks of veins and a wider range of superficial deposits.

Jan 1, 1963

By John C. Machisak

THIS INFORMATION CIRCULAR contains injury and employment data for all stone quarries in the United States for the Calendar year 1960. This publication contains statistical data on injuries and employment pertinent to the stone quarries and related operations, such as the manufacture of cement and lime, rock dressing etc., but excludes statistics for clay and sand and gravel operations. Data for these commodities may be found in other Bureau publications. Reports received from the operators are voluntary responses to the Bureau's request for information; therefore, the figures may not be complete for the industry. However, since these data contribute greatly to the promotion of safety, every effort has been made to make them representative of the industry.

Jan 1, 1963

The Ediacara mineral field is classified as a Mississippi Valley type deposit with stratiform mineralization near the base of the Cambrian beds. Mineral deposition was contemporaneous with sedmentation and reerystallization, and mobilization took place after lithification of the sediments. Several mechanisms of deposition were possible.INTRODUCTIONThe Ediacara mineral field is located in the Mt. James Range approximately 300 miles north of Adelaide, about 12 miles west of Beltana railway siding and 10 miles east of Lake Torrens. It is isolated geographically from similar deposits of equivalent age and environment in the Flinders Range Province (Fig. 1). The climate may be described as semi arid with high summer temperatures and frequent dust storms. Occasional thunder storms are the main source of rain in the summer months.The exact date of discovery is unknown, but is believed to be about middle of the last century. Ulrich (1872) was the first geologist to report on the field. At that time only the southern portion of the field had been prospected (and abandoned). Although the prospects did not appear encouraging Ulrich advised prospecting of the shales and testing beneath the limestone.In 1888, Rosewarne, an Inspector of Mines, visited the Southern Workings and queried whether they were connected with some lode at deeper level or were merely bedded deposits. The first geological map with sections was drawn by H.Y.L. Brown (Brown 1892).Brown recognized three principal rock formations as dolomitic sandstone, kaolinised shales and sandstone, and quartzites and sandstone in descending order. These three basic units are still recognized. He recognized also the stratiform nature of the mineralization in the shales as a...

Jan 1, 1963

By Allan F. Smith

The influence of hydraulic fluids on spontaneous heating in bituminous coals is determined by measurement of the temperature increases produced in coal-fluid mixtures heated to a temperature sufficient for the initiation of self-heating. Similar tests on as-received coal samples and water-coal mixtures are compared with the results obtained for the various hydraulic fluids. Three of the four coals were sampled from coalbeds known to have a history of spontaneous heating. The data provide a basis for predicting the possible effects in gob or carbonaceous refuse of coal mines.

Jan 1, 1963

By James A. Wasson

This report summarizes the results and conclusions reached by various investigators who have attempted to determine the extent to which hydraulic fracturing will affect the secondary recovery of crude oil by waterflooding. It also discusses the most advantageous use of this well-stimulation method in waterflood projects. A thorough search of the literature was made, and pertinent information was abstracted from appropriate reports. A carefully designed and controlled program of formation fracturing is an effective aid in waterflooding because it increases water-injection and oil- production rates. Generally, fracturing has resulted in little or no reduction in ultimate oil recovery, but under certain circumstances recovery has been substantially increased.

Jan 1, 1963

By Tanner A. C, Harraway D. H

Various circuits were tried at Mount Isa Mines during the period 1959 to 19G3 with the objective of improving the differential flotation of galena and sphalerite. Many benefits and disadvantages of the various circuits were revealed. An analysis' of ore characteristics and their effect on flotation was made -and resullted in the design of a proposed circuit which is currently in the process of installation.INTRODUCTIONSince 1936 when lead-zinc sulphide flotation commenced at Mount Isa, at least three types of ore have been encountered.Each ore has presented problems to flotation metallurgists.The three types of ore are,1. partially oxidized upper level sulphide ore,2. Black Star ore from the lower levels with its carbonaceous fraction, and3. Black Rock ore which is similar to 2, but more free milling.In retrospect a number of the metallurgical successes of the past were short lived. Often flowsheets or 0perating practices were designed to solve a single metallurgical problem associated with the current ore being treated. As the ore changed the problem would vanish and the method originally taken to counter the problem could become unnecessary or deleterious to the treatment of the new ore. The general lesson learnt from-the past-is-that thetreatment of Mount Isa lead-zinc ore involves a number of equally major problems...

Jan 1, 1963

Some 50 miles of tunnel have been driven in the Snowy Mountains Area since tunnelling commenced in 1951. Hates have improved progressively due to the know-how of American supervision and use of large matched equipment of modern design.The work has been carried out by contractors, working almost exclusively under schedule of rates contracts. The Authority has maintained active research into tunnelling problems, especially that of support, and this has resulted in considerable economies and improved rates of progress. The contractors also have sought economies both by management and equipment techniques. Ammonium nitrate came into favour as an explosive essentially because of its lower cost, and handling techniques have improved progressively. Rock conditions preclude use of the "Mole" type equipment in its present stage of development, but one contractor introduced the "sliding floor" and this could exert a great influence on future tunnelling methods.Examination of tunnels that have been in service for some time confirmed the quality of the work and endorsed the policy of continued research and development.GENEHALThe Snowy Mountains Scheme provides for the diversion of the Snowy and Eucumbene waters through two transmountain tunnels to the western river systems. These diversions, together with additional regulations provided for waters already flowing inland, will provide an average additional discharge of 1,818,000 ac it per year for irrigation.Furthermore, approximately 6,000 million kWh of electrical energy will be generated annually in power stations with a total installed capacity of some 3,000,000 kW (Fig. 1.).INVESTIGATIONThe aim of investigation work is firstly to collect sufficient information to allow the overall scheme to be planned and then to follow up with detailed information on eachproject. The correct balance for all aspects of this work is a matter for keen judgment, as the tunnels must be planned...

Jan 1, 1963

By Edna A. Dancy, Gerhard J. Derge

Jan 1, 1963

By H. H. Dreissen, F. J. Fontein

The operating principle of the classifying cyclone has been described often but some special aspects of the cyclone receive further clarification here. In addition, several uses of the classifiers are summarized and made clear by means of practical examples. In coal and ore washeries, the washing cyclone is widely used for the separation by specific gravity of sizes up to about 12 mm. This application has lately been extended to the separation by specific gravity of particles up to about 50 mm. This use makes special demands on the construction and wear resistance of the cyclone. The sieve bend, a development of the Dutch State Mines which is less well known than the hydrocy-clone, is dealt with at some length. The sieve bend is an apparatus designed for wet screening. Attention is given to the variables influencing the performance of the sieve bend. Hydrocyclones are now so widely applied that it would be difficult to find an industry not, directly or indirectly, using them or knowing how to use them since publications on this subject abound.1-3,5,9-11,13-15 However, because of the large number of variables influencing the operation of classifying cyclones, it is not entirely possible to calculate the results of this type of cyclone. Therefore, a number of lesser known variables will be discussed here along with some special applications of the classifying cyclone. FACTORS INFLUENCING CYCLONE CLASSIFICATION Shape of Particles: The shape of particles may cause a much coarser classification than the one expected, considering the sieve analysis and the cyclone dimensions chosen. This was clearly shown by feeding a mixture of spheres and disks in water into a cyclone. The spheres were 0.36 mm diam and the disks, 3 mm diam and 0.03 mm thick. These dimensions were chosen in order that the disks and spheres might have the same rates of fall under gravity. Both spheres and disks had a specific gravity of 1.05. The results obtained with these particles in a cyclone are summarized in Table I. Test No. 2 shows that the catch of spheres was

Jan 1, 1963