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By Bunting S. Crocker

Bunting S. Crocker (Executive Vice President, Kilborn Engineering Ltd., Toronto, Ont., Canada)-This is an interesting report on laboratory-scale testing with pebble charges in 12-in.-diam mills, and the author correctly concludes that useful laboratory testing can be done. In the opening paragraphs he states, "laboratory pebble-milling tests have been considered too difficult to perform and not relevant enough to the actual grinding situation"!! This is definitely not so! The writer published detailed tests done in a 12-in.-diam mill comparing pebble and steel balls in 1952 6 and again in 1954 7. We note that our review paper in 1963 was the only one mentioned in the References. The author states that "a smooth lining is more frequently used in commercial-scale pebble grinding." The writer has designed some 22 plants treating 134,000 tpd in North America and Australia. He has also visited pebble installations in Norway, Sweden, Finland, and South Africa. All these plants correctly use heavier lifters than would be considered standard for ball mills of a similar size. Smooth liners are not recommended in wet ore treating plants. In the 1952 paper6 it was clearly demonstrated in the test work that the individual ore pebbles had to be the same weight-not the same diameter or size-as the steel balls if comparable grinding results were to be obtained. In the tests performed in this study most of the pebbles "passed 50-mm round hole screen openings and remained on a 40-mm round hole sieve. Correspondingly most of the ball mill experiments were performed with 50 or 40-mm steel balls". Thus, the balls and pebbles were essentially the same size or diameter. This means we are comparing apples and oranges. When the feed being ground is fine enough the pebbles will be superior. When the feed is coarse the steel balls will be the better. This is similar to grinding tests in which two sizes of steel balls are compared. In the middle of the article, "Crocker5 has reported that equal weights of pebbles and steel balls achieve the same grinding capacities under similar conditions …", then he proceeds to question this postulate. In the eight reports that I have published, I have never made this statement. What I have said is "for comparable grinding, the individual pebbles in the mill charge should be the same weight as the individual steel balls." This is not the first time that I have been misquoted on this point! It is most unfortunate that this test work has been done with a ball and pebble of the same diameter and not the same weight. It is impossible to properly evaluate the results. I also regret the fact that the screen analyses of the tests were not shown. Many of us who have been 40 years or less in the grinding game can easily read screen analyses at a glance. We can tell whether the top meshes are being ground by the ball charge, etc., etc. The graphs are fine for the summary or to illustrate conclusions but are often misleading in the report itself. However, we do agree that useful pebble grinding tests can be done in a 12-in. mill.

Jan 1, 1973

The selected list of sources of information on geology and mining in this section is provided to facilitate locating the major governmental and private entities in position to furnish such information, including societies and institutes; colleges, universities and technical schools; and magazines, yearbooks and mine directories, plus a number of general texts. In the case of publications, it should be noted that, in addition to those listed, most of the governmental and private organizations publish a wide variety of reports, bulletins, monographs, surveys and the like, including, in the case of governmental agencies, production statistics. The names of the mining schools and colleges in the following, with some exceptions, were taken from the International Handbook of Universities and & her Institutions of Higher Learning, and the Commonwealth Universities Yearbook, with the kind permission of the International Association of Universities, Paris, and the Association of Commonwealth Universities, London, owners of the copyrights. Abbreviations in the listings include the following: A. P., B. P, and C. P., Apartado Postal, Boite Postal and Caixa Postal (post office boxes); Br., Branch; and F., Faculty.

Jan 1, 1973

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

3. Preliminary Evaluation of Mine Sealing Techniques As the first stage in the development of a technique for the remote sealing of mines, a state-of-the-art survey of various mine sealing techniques was conducted. This was expanded to include a review of different materials offering some potential for use as a mine sealant. Techniques for the remote placement of materials for other applications were evaluated, and system concepts for dis¬tributing remotely placed materials were developed. This preliminary review led to the development of a functional description of a general mine sealing technique to meet the specified conditions. Various potential system configurations were synthesized. These were subjected to a preliminary evaluation based on estimated confidence in system performance, development risk, cost, and sealing time. Based on this preliminary evaluation, promising mine¬sealing techniques were selected for further development. This section presents a review of the following: (a) Techniques for constructing permanent seals from within a mine. (b) State of the art in remote sealing for mine fire control. (c) Techniques for remote placement of materials for other applications. (d) Systems for distributing remotely placed material. (e) Materials for mine sealing. (f) Synthesis of remote mine sealing concepts.

Jan 1, 1973

By Michael W. Redifer

A Fortran IV computer program was developed to calculate the composition at equilibrium of products from a set of high-temperature gas combustion reactions. The program was used to develop high-temperature equilibrium concentration profiles for various constituents as a function of temperature and oxygen concentration. The computer program was specifically applied to reactions pertaining to the corrosion of superheater tubes in pulverized coal-fired boilers; however, it is useful for any multicomponent, multireaction scheme in which equilibrium constant data can be obtained and is comprised of gaseous reactants along with finely dispersed solids or liquids. General applicability of the computer program, including its limitations, are discussed along with detailed instructions for using the program.

Jan 1, 1973

By S. R. Krogh, T. O. Olsen

Analytical expressions for the breakage rate as functions of mill charge, mill speed, particle size, ball diameter, and ball load are derived, using idealized models for probability of breakage (Gaudin and Meloy), energy distribution (Mempel), and arithmetic mean of effective ball energy (Langemanns). Computational results using the theoretical equations are compared to experiments. The equations enable simulation of ball mill grinding at different grinding conditions.

Jan 1, 1973

By Ernest M. Spokes, Martin A. Thieme

A simulation model developed to analyze scraper-pusher utilization in open pit mining systems is described. The mining simulator discussed was developed as a tool to aid management in evaluating alternative open pit haulage schemes and to reduce the risk involved in the selection of equipment.

Jan 1, 1973

The application of biogeochemical methods in mineral exploration in semi-arid to arid environments in Western Australia has been investigated in an area near Norseman.The study involved a comparison of trace element characteristics of rock, soil and plants in the vicinity of the Pioneer BB prospect, where nickel-iron sulphide mineralization occurs in a "greenstone" sequence of ultrabasic, basic and sedimentary rocks.Analyses of unweathered and partly weathered rock from diamond drill cores show the ultrabasic rock to be highly variable with respect to Ni, Cu, Co, Zn and Mn.Samples of weathered bedrock and overlying soil were analysed for total trace element contents and for the trace elements associated with secondary iron and manganese oxides. Approximately 30 per cent of the total nickel content of the weathered basic rock is associated with secondary iron and manganese oxides, compared with approximately 15 per cent in the weathered ultrabasic rock.The soil has a sufficient residual content to provide a reliable indication of the chemistry of the underlying rock. Total trace element analyses of the -89 mesh fraction show strong anomalies for nickel and copper over the mineralized zone. Important amounts of nickel, cobalt and, to a lesser extent, copper are apparently associated with secondary iron and manganese oxides in the soil.Melaleuca sheathiana (tea tree) has been used to study the relationship between soil and plant chemistry. No strong relationship between plant and rock type was observed. Analyses were made of leaves, twigs, wood, bark and roots, and all plant organs were found to have anomalous nickel and copper contents near the mineralized zone. Leaves were found to give the best contrast in the anomalous area and to show fewer erratic values than other organs. It is concluded that the uptake of trace elements by tea tree is low in the semi-arid to arid environment of Western Australia, but that analyses of the plants do reflect the presence of mineralization.

Jan 1, 1973

By F. E. Joyce

This paper describes the development of a process for producing manganese and iron pellet concentrates from low-grade manganiferous iron ores of the Cuyuna range by a two-stage sulfatization-reduction roast. First, the manganese minerals (7.5 percent manganese) were converted to water-soluble manganese sulfate by roasting in sulfur oxide gases at 700° C, then, the hematitic iron minerals (31 percent iron) in the hot sulfatized are were reduced to magnetite with simulated reformed natural gas in the temperature range of 350° to 425° C. Batch tests were made in a 3-inch-ID by 6-inch-long, gas-heated, stainless steel retort, and continuous countercurrent experiments were performed in a 2-inch-ID by 10-foot-long, electrically heated shaft furnace. Manganese sulfate was removed from the roasted product by leaching with water, and over 90 percent of the manganese was recovered in an oxide product (65 percent manganese) obtained by precipitation, drying, and thelmal decomposition of the sulfate. An iron oxide concentrate (60 percent iron) with an iron recovery of 75 percent was obtained from the water-insoluble residue by magnetic separation.

Jan 1, 1973

By Robert M. Cox

Systematic roof bolting has proven to be a very effective method of mine roof control; however, major roof failures still occur and roof falls still remain the number one occupational hazard of underground miners. Why do some bolted mine roofs fail, while the vast majority of bolted mine roof remains stable and safe to work under? Observations of numerous roof failures indicate that most of the major roof failures* are associated with either: 1) Jointing, faulting or other structural fracture zones; 2) massive shale beds of lenticular structure, or 3) thinly laminated sand-shales. The jointing and faulting present an obvious weakness in the roof rock structure; whereas, the massive shales and laminated sandy-shales create a roof structure with low shear strength and/or modulus of deformation. An observation of major significance is that most bolted mine roofs fail as a unit, and that the thickness of the fall is roughly equivalent to the roof bolt length (See Figure 1). In fact, several operators have experienced the phenomenon of an increase in roof fall thickness with an increase in roof bolt length.

Jan 1, 1973

By Wasp E. J

A review is given of recent commercial long distance slurry pipeline systems in- stalled worldwide. The technological advan- ces in slurry engineering and system opera- tion are discussed, together with a brief re- view of the economics of slurry transportation and future trends in the industry.

Jan 1, 1973

Investigation of standard tests used to establish the decrepitation rating of Western Australian iron ore showed scatter in results which could be reduced by textural type sampling. Testing of individual textural types resulted in separation.of a range of decrepitation behaviour patterns. No unique correlation was established between water content in goethite, or between any single mechanism and breakage in shock heating. The latter depends rather on several mechan- isms whose operation is controlled by the texture of the ore. Texture studies were used successfully to predict decrepitation behaviour which could be related to orebody structure for mine planning, and blending for sales or processing requirements.

Jan 1, 1973

The results of self potential geophysical surveys conducted over base metal prospects near Orange, Goulburn, and Wellington, N.S.W., indicate that this rapid and inexpensive exploration procedure merits wider application within eastern New South Wales, and in similar environments elsewhere.

Jan 1, 1973

An underground storage and filling distribution system is presently being established at North Broken Hill Limited in the No.3 Shaft area. This has been necessitat- ed by the dependence of the present filling system on the No.2 Shaft and its imminent closure due to cessation of production. The storage will consist of three tanks excavated in low grade ore, between the No.20 and No.21 levels, at approximately 2700 feet below the surface. The tanks will each have a capacity of 1500 cu yds. Consideration was given for surface storage, although under- ground storage was thought to have greater merits. Two tanks have been excavated, and are in operation. Three or more outlets are installed beneath each tank, with horizontal connections into the No.21 level 'mixing box'. Water decants from the top of the fill in the tanks, and passes into a decant water sump, at the bottom of which is a borehole to the No.21 level. This is then connected to the mixing box and water used as make-up water with the semiwet solids for transport into the existing pipe distribution system. Preliminary results of the system have been satisfactory and it is envisaged that this system will readily cope with the filling demands of the future.

Jan 1, 1973

By Primak. George J.

"In the development of a new product as well as during its introduction on the market, it is very important to give due consideration to problems involving patents, licenses and trade marks. At the very beginning of the research and development program, it is obviously essential to ascertain, through a suitable patent search, that the product in question will not infringe any patents which are still in force. Then, a possibility of achieving one's own patent or proprietary position on the product or the process of its manufacture should be carefully explored. Licensing arrangements that one may reach with respect to patents and know-how covering such new product may, in the final analysis, determine its over-all success or failure. If one can count on licensing revenues or some favourable cross-licensing arrangements with respect to a newly developed product, this may go a long way to achieving profitability and success. The selection of a good trade mark is probably one of the most important acts that one has to perform once the product is developed, as customers will identify the new product by such a trade mark. In many instances, successful marketing and widespread acceptance of a product are largely due to its appealing name or trade mark, accompanied by proper promotion and advertising. Once the trade mark has been adopted, it should be registered in the Trade Marks Office to provide the protection afforded by federal statute. If the product is to be manufactured, sold or licensed in some other countries, similar considerations should be made with regard to each such country."

Jan 1, 1973

By R. F. Frantz, T. P. McNulty

The upper-level mineralization of the din Buttes, Arizona copper orebody consists primarily of dilute copper silicate impregnation in fault clay and throughout the altered limestone hostrock. Cuprite and native copper are minor with true chrysocolla rare. Owing to the high calcium carbonate and to the hydrogen ion exchange capacity of the clays, acid leaching would be economical only with cheap acid available. Leaching of the silicate copper with reagents other than sulfuric acid is slow and incomplete unless the ore is first heated to disorder the mineralized grains and to reduce partially the contained copper. Following heat treatment, 70 to 90 percent of the nonsulfide copper can be dissolved in aqueous anrmonium carbonate. Recovery of a pregnant solution by counter-current decantation is effective provided ammonium carbonate solution is added to the washing stages in order to oppose adsorption of dissolved copper by clays in the residue. Thermal stripping of the pregnant solution permits recovery of ammonia and carbon dioxide while precipitating copper either as oxide or carbonate. The research program was carried from batch tests through continuous miniplant operation to a five-month campaign in a 20 TPD continuous pilot plant. Pilot plant results, the relationships among key varibles, and a detailed flowsheet are given.

Jan 1, 1973

By Reynold Q. Shotts

One often sees in the papers, in these days of ecological consciousness, estimates of the quantity of land that has been "devasted," "ruined," or "destroyed," by surface or strip mining, especially for coal. One feels sure that coal miners must have been the first to discover the art of excavation and that the public didn't know of its existance until five or 10 years ago! Estimates of the acreage vary widely with most of them sounding somewhat unreal. One estimate of 175,000 acres in Alabama appeared in one newspaper article and the implication was that all of this was mining for coal. The question was raised anew last summer when the author began working on a land use estimate utilizing aerial photographs, a preliminary project to the Alabama Earth Resources Technology Satellite (ERTS) contract presently being fulfilled. One land use category was barren or waste land and aside from some sand beaches in the two coastal counties in Alabama, recently strip mined land constituted most of that category. It quickly became apparent that old stripping was very hard to detect so that estimates from aerial photographs are not accurate. With regard to relatively new stripping, a thin veneer of reflective dirt washed over the countryside may result in a considerable overestimate of the excavated area. Actually, there is a way to estimate the area excavated by strip mining using published Bureau of Mines figures. At least three sets of data are needed: (1) Coal production figures, (2) average thickness of coalbeds mined, and (3) an accurate recovery figure.

Jan 1, 1973

By C. M. McCulloch

A geologic study of Mines 32 and 33 in Cambria County, Pa., was conducted as part of a methane control research program. Areas of high methane emission and roof instability are encountered which are related to the structural and stratigraphic features that characterize the geologic setting of these mines. Locally the folds trend N 20° E ±2°, the direction of the butt cleat in the Lower Kittanning coal. The face cleat strikes at N 69° W ±2° and the systematic rock joint in the surface bedrock strikes N 67° W ±2°. This suggests that a directional stress oriented N 70° W produced the folds and influenced the directions of coal cleat and systematic joint sets. Analysis of SLAR indicates three directions of prominent regional lineation: N 39° E, N 31° W, and N 70° W. Little gas was encountered during development mining; large volumes of gas are encountered when roof falls. Most of the gas comes from strata above the mined coal; therefore, to control methane, roof instability must be controlled. Roof falls and high rates of methane emission are most likely where less than 30 feet of many thin layers of limestone, shale, and sandstone occurs between the Lower Kittanning coal and the next coal and in zones along the margins of a sandstone channel.

Jan 1, 1973

By John M. Heckard

It all started with the National Environmental Policy Act of 1969, which establishes that Congress is committed to restore and maintain environ- mental quality. It directs all federal agencies to identify and develop methods and procedures so that environmental parameters and values will be given equal consideration in the decision-making process, along with economic and technical parameters. Section 102 of the Act directs, among other things, that all agencies will submit a detailed statement on: (1) the environmental impact of the proposed action, (2) any adverse environmental effects which cannot be avoided should the proposal be implemented, (3) alternatives to the proposed action, (4) the relationship between local short term uses of man's environment and the maintenance and enhancement of long term productivity, (5) any irreversible and irretrievable committments of resources which would be involved in the proposed action should it be implemented. Passage of this act has been followed by other legislation, both federal and state. The Water Quality Act of 1970 puts teeth into the previously existing Federal Water Pollution Control Act by requiring a "certificate of reasonable assurance that the activity licensed will not violate the applicable water quality standards." The Clean Air Act of 1970 requires that the Environ- mental Protection Agency establish national air quality standards, as well as standards for significant new pollution sources.

Jan 1, 1973

By R. O. Burt, D. J. Ottley

"SYNOPSISRecent developments in the use of the Bartles-Mozley table and the Bartles CTS screen are described for the gravity preconcentration of fine heavy mineral and metal particles present in low grade pulps. The B-M table is a relatively new device used for the recovery of particles of up to 100 micron size down to 5 microns or in the case of gold and platinum, down to 1 micron. The CTS screen is a wet screening device used for feed preparation ahead of the Bartles-Mozley table and will size effectively down to about 300 mesh. Results and operating data for a number of different materials are given including outline flowsheets; the effects of the major variables on the performance of the table are briefly discussed. The potential of the B-M table to treat a variety of different ores, coal, tailings, and waste products are considered. The utilization of the B-M table in association with other unit processes to improve overall results as well as to improve the economics of design and performance of plants are also mentioned.INTRODUCTIONA number of new gravity concentration devices have been developed in recent years for the recovery of fine heavy mineral and metal particles but for reasons which include low capacity, high capital or operating costs, competition from other and better processes, the absence of simplicity or reliability in operation etc., only a few which include the Bartles-Mozley table, have been proved to be of commercial application.The name of the machine is derived from the inventors name, Richard Mozley, who developed the B-M table at the University of Bristol in England. The table was subsequently taken up and patented, world-wide, by the National Research Development Corporation a British government agency. An exclusive license to manufacture the table was granted by NRDC to Bartles (Carn Brea) Ltd. in Cornwall, England."

Jan 1, 1973

The use of the heavy media cyclone (HMC) Separation process for the treatment of ores in a particular size range is comparatively new to Australia. The paper describes briefly the principles of HMC operation. Reference is made to early development work, the pilot plant trials and the acceptance of the technique as a mineral dressing process. The Mitchell Cotts pilot plant at Amdel is described briefly and the results of test work on this unit for the processing of a wide variety of ores and ore types are given. Comments are made on the ob- jectives aimed at in the investigation and results are discussed with particular reference to behaviourial differences between ore types. The process is easy to operate, possesses a high capacity-to-unit-size rating and is capable of a high degree of flexibility. Further developments such as specially prepared and graded media for specific applications, automatic media density control and regulation of media consistency by the use of surface ac- tive agents and polymers have increased versa- tility and sensitivity of control to the point where products differing by as little as 0.02 of a specific gravity unit can now be separated with ease.

Jan 1, 1973