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By M. Fan, M. Mankosa, G. Luttrell

"Column and other non-conventional flotation approaches continue to provide benefits where conventional flotation processes have exhibited limited success. This is particularly evident with respect to flotation of ultrafine and coarse particles. Advancements in air sparging technology have provided the ability to produce finer bubbles than previously possible. The generation of finer bubbles coupled with the froth washing capabilities of a flotation column has demonstrated improvements in ultrafine particle recovery while simultaneously producing a high-grade float product. On the other side of the spectrum, the use of these sparging technologies while applying flotation fundamentals to a fluidized-bed reactor has increased the maximum floatable particle size up to and in excess of 3 mm. Benefits of higher recoveries and reduced reagent consumption have resulted from the use of these technologies. An additional benefit includes a reduction in plant grinding requirements. As such, this paper describes the application of Cavitation-Tube sparger technology and fluidized-bed flotation (HydroFloat). A review of data from industrial and pilot-scale applications is also provided.INTRODUCTIONConventional (mechanical) froth flotation is considered the workhorse of the minerals processing industry. This low-cost process makes it possible to selectively recover minerals by exploiting the difference in surface characteristics (e.g., wettability) of the valuable component and the waste material. Unfortunately, the upper particle size limit for flotation rarely exceeds 0.600 mm, and is typically maintained at less than 0.300 mm for most industrial applications. For many commercial base metal plants, the particle size range for optimum recovery is typically between 0.01 and 0.1 mm (Lynch et al., 1981). This finding is not novel. In fact, the effect of particle size on flotation recovery was studied as early as 1931 by Gaudin et al. who showed that coarse (+0.250 mm) and extremely fine particles (-0.010 mm) are more difficult to recover than particles of an intermediate size. The loss of recovery is due to inherent limitations associated with the flotation process, including bubble-particle adhesion and collision, detachment, buoyancy, and transport."

Jan 1, 2010

The following pages discuss the objectives, the background, the scope and a statement of the problem of the study of methods to improve the pillar extraction practices in underground coal mines. 1. OBJECTIVES The objectives of this project were: ? to determine the principal factors contributing to high accident frequency and severity in both conventional and continuous mining operations; ? to compare and evaluate the safety aspects of the "open end" and "split and fender" systems of pillar mining; to establish basic data required to decide what constitutes an adequate pillaring plan that will optimize efficiency, recovery, and safety; ? to determine what measurements or information should be collected, (e.g. roof sag, pillar stress,) to make on-the-spot judgment of impending roof or pillar collapse; ? to make recommendations to improve existing methods or to insure proper techniques are implemented, and ? to suggest areas where additional studies or new research may be of value.

Jan 1, 1975

By Sanjeeva Latchireddi

"Deteriorating ore grade and high demand of metals has tremendously influenced the unit capacity of SAG mills. Pebble circuits have been added to the existing SAG circuits to increase their unit capacity. To make the pebble circuits justifiable, the grate openings are increased almost to 4.5 inches to draw large quantity of pebbles. The inherent transportation problems associated with SAG mills in closed circuit with pebble fraction are more complicated than the single stage SAG mill operation, because the coarse pebbles behave significantly different to that of slurry in pulp lifters. In addition, operation of mills at higher speed, to take advantage of precise design of high release angled shell lifters significantly reduces the discharge efficiency of the conventional pulp dischargers. The presence of a sizable quantity of pebbles in the pulp lifter limits the space available and reduces the flow gradient through the grate thus increases the load inside the mill and hence the mill power-draw. This paper analyses all the problems associated in discharge of slurry and pebbles in SAG mills with pebble circuits. The Outokumpu patented Turbo Pulp Lifter (TPLTM) aims at eliminating the inherent material transport problems to ensure good grinding conditions. Recent installation of TPLTM in a 26-ft SAG mill has proven these claims by reducing the specific power consumption while increasing the mill capacity.INTRODUCTIONThe conventional wisdom is to look at the semi-autogenous grinding (SAG) mill as just another grinding mill in which ball charge, mill filling, and mill speed are varied to attain maximum throughput. Liner design for the SAG was also approached more from a wear perspective rather than a metallurgical and hydraulic-flow perspective. The extensive research work carried out by Latchireddi and Morrell (1997,2003a and 2003b) has demonstrated to think of the SAG as more of a pump in which the grates and pulp discharger end (“impeller”) were designed to efficiently discharge the product sized particles smaller than the grate size with minimal recirculation out of the mill.The rock load in the mill is essentially depends on ore characteristics and the discharge rate of broken particles. The discharge rate of the product material depends on how efficiently the discharge pump (grate and pulp lifters) is operating. Similar to the impeller design affecting the pump capacity, the pulp lifter design affects the discharge capacity (or mill throughput) of the SAG/AG grinding mills. The general arrangement of AG/SAG mills discharge system is shown in Figure 1."

Jan 1, 2007

By Stephen A. Orr

Underground mining is a dynamic art and science with a diverse set of design, production, and economic criteria that must be considered before selecting an optimal method to extract the ore. While all methods can be technically classified as either self-supported, supported, or caving, the multitude of subsystems and existing variations bear witness to the fact that each orebody is unique and, as such, justifies an individual approach to optimize mineral extraction. In this sense, underground mining is an art. The ability to evaluate the unique characteristics of each ore body and utilize sound engineering principles to design the optimal system constitutes effective method selection. The task by no means ends at this juncture, however. Subsequent implementation requires an ability for modification. Very rarely are all the facts available to make a concrete decision prior to development of the resource. As a result, the risk of a wrong decision can never be eliminated. This requires a significant degree of flexibility with each method. Each unit of exploration, development, or exploitation work contributed to a deposit enhances knowledge of the ore body. The best mining methods are those that correctly account for the known parameters but provide an allowance for change at minimal cost and adapt to unanticipated conditions.

Jan 1, 2008

By J. L. Christie, R. H. Leach

SO much has been written recently about the use of silver to replace scarce metals that certain facts about silver and its uses should be of interest. Figures for the production and use of silver, taken from the Handy & Harman annual reviews of the silver market, are given in Table 1. It will be seen that the rate of production has remained fairly constant and has been affected in recent years by the production of base metals, of which silver is a by-product. In each of the years 1937, 1938, and 1939, the U.S. Government acquisitions alone exceeded the entire world production, the difference, of course, being made up by imports of previously accumulated stocks. In 1940 and 1941 the U. S. Government acquisitions plus the United States and Canadian uses in the arts and industries exceeded the Western Hemisphere production. The U.S. Government pays a premium price for silver newly mined in the United States, at present 71.11c. compared with the price of 35'/8c. for foreign silver, with the result that the current U. S. production is not used commercially for the arts and industries. At the time this is written (June 1942) there is much uncertainty as to the future effect of this situation.

Jan 1, 1942

By G. M. Schwartz

THERE has been considerable controversy regarding the structure and mineral constituents produced when iron ore is sintered. This investigation was undertaken in order to establish the fundamental reactions that take place in the sintering process by determining the nature of the resulting minerals. The writer's immediate interest in the subject arose mainly from the request of E. W. Davis for information based on a microscopic study of sinter submitted by him in May, 1926. In the author's preliminary work, samples of iron-ore sinter were secured from the Minnesota School of Mines Experiment Station and from commercial plants. These were polished by the usual methods for polishing opaque ores. In order to study these surfaces satisfactorily, it is necessary to magnify them rather highly, a range from 100 to 1000 dia. being used. For the higher magnifications oil-immersion lenses and an intense source of light are necessary. After the preliminary study had shown the problems involved, a series of small samples were sintered under carefully controlled conditions and with analyzed materials. Variations in the relative amounts of ore, coal and water were made in order to study the effect of each constituent. The attempt has been to arrive at a clearer understanding of the sintering process and the reactions involved without reference to any preconceived notion as to sinter. It is clear that the study of polished surfaces has yielded results not possible with thin sections alone. The thin sections made in this work were found unsatisfactory at magnification greater than 75, whereas magnifications of 1000 were easily studied with reflected light on carefully polished surfaces. A rather complete statement of observed facts is made so that the reader may form his own conclusions. The writer's interpretations are suggested.

Jan 1, 1929

By A. J. Williams

"Conventional base metal milling practice normally consists of crushing, grinding and cyclone classification followed by flotation. It is the authors' belief that the commencement of flotation after cyclone classification leads to inferior metallurgical results and that implementation of flotation of grinding mill discharges can result in increased recovery due to reduced overgrinding, reduced activation of contaminating minerals and improved dewatering circuit results due to the production of coarser concentrates.The concept of recovering minerals from the discharge of grinding mills is not new! Gold concentrators have utilized jigs and flotation cells while iron ore plants have employed magnetic separators to recover gold and magnetite respectively from the discharge of grinding mills. More recently, a Reichert cone has been used to recover sulphide and oxide base metal minerals from screened rod mill discharge. 1To the authors' knowledge, the first application of flotation of base metal minerals from the discharge of a production plant grinding mill was at the Lake Dufault concentrator of Corpor'1tion Falcon bridge Copper. Located 10 miles north of Noranda, Quebec the Lake Dufault concentrator commenced operations in August, 1964.The installation of flot11tion cells in the Lake Dufault grinding circuit proved so successful that an identical system was installed in the Manibridge concentrator of Falconbridge Nickel Mines Limited. Located 90 miles southwest of Thompson, Manitoba the Mamibridge concentrator commenced operations in June, 1971 and due to exhaustion of economic ore reserves discontinued production in May 1977."

Jan 1, 1984

By Mike Ounpuu

"Locked cycle testing has become more common practice in the last 10 years. Reasons vary from a desire to avoid pilot plant testing, demand for more variability testing within deposits, and perhaps most importantly, a request from the financial institutions who invariably finance many of the projects. Surprisingly, many people don’t understand locked cycle testing, analysis and balancing. This paper provides a brief overview of locked cycle testing, and then progresses into a more detailed discussion on the analysis and balancing of locked cycle test data. The paper endeavors to educate CMP personnel on how to determine if the test was good and if a reasonable metallurgical projection was made. The paper uses case studies to illustrate the key points.INTRODUCTIONA locked cycle test is a repetitive batch used to simulate a continuous circuit. The basic procedure has a complete batch test performed in the first cycle which is then followed by similar batch tests which have “intermediate” material from the previous cycle added to the appropriate location in the current cycle. These batch tests, or cycles, are continued in this iterative manner for an arbitrary number of cycles. The final products from each cycle, i.e. final concentrate and final tailings, are filtered and thus removed from further processing. At the end of the test, all the products, final and intermediate, are dried, weighed and subjected to chemical analysis. The test is balanced and a metallurgical projection is made.This description can be found in many of our classical textbooks for the mineral engineer 1, 2, 3,4. Unfortunately, none of these textbooks provide any discussion beyond the basic procedure. Often, they provide comments such as in Taggart’ where he states; “It is questionable whether in any case it approximates mill results any more closely than the standard batch test”. It is truly surprising that our classic textbooks promote that locked cycle tests are more art than science, and suggest that they can be of dubious value. None of the textbooks provide meaningful insight or discussion in how to assess:"

Jan 1, 2001

Jan 1, 1988

The mineralogy of nickel slags from the flash smelter of Western Mining Corporation Ltd. at Kalgoorlie was studied. Residual magnesium silicates in the sulphide concentrates raise the melting point of the slag and result in the formation of magnesium-rich olivines. Addition of lime lowered the melting point, and, in slowly cooled slags, resulted in the formation of a pyroxene.Magnetite and sulphides were also present in all slags.The converter slags contained an olivine near fayalite in composition, together with wiistite, magnetite, and a little sulphide.Accretions from the hearth of the flash furnace were largely composed of magnetite with subsidiary olivine similar in composition to those of the flash furnace slags.Wall deposits, however, were largely composed of nickel ferrite and nickel-iron olivines.

Jan 1, 1976

By Wm. Mark Hart

High horizontal stresses and shear failure have been considered the major reasons that cause entry roof failure and falls for underground mining. Therefore, reorientation of the current mining systems or layouts or using angular crosscuts in mains or gate entries becomes more popular if a greater than normal horizontal stress is measured. However, reorientation of the current mining systems or layouts is always expensive and use of the angular crosscuts may weaken the pillar structure at corners. Therefore, cautions must be taken before any decision related to reorientation of the current mining systems or layouts or use of angular crosscuts is going to be made. In order to prevent entry roof failure and falls, the following two issues must be carefully examined and fully understood: 1. Which one, shear stress or tensile stress, is going to be blamed for entry roof failure? 2. Which one, horizontal stress, vertical stress, or local geological weakness plays a major role in entry roof failure and falls? This paper analyzes the mechanisms of entry roof failure and falls for underground mining in general examines the roof fall history at Springvale Colliery, and proposes the means of preventing roof failure and controlling roof falls for Spingvale Colliery in particular.

Jan 1, 1996

By Ann Barron

For millions of people, cold weather is a fact of line – and one that can make a major challenge out of just getting to work. But for those working in the blasting industry, a number of obstacles are created when old man winter blows in. In addition to the obvious concerns regarding personal protection, Mother Nature can throw some very nasty weather at the blasting crew trying to travel with explosives products from the magazine site to the job site. As such, divers need to be familiar with cold, ice, and snow driving conditions both on and off the blast site. It’s critical to know what to expect before you leave. Keep informed of the latest weather and road conditions as they change often; it will help you make the right choice in clothing and driving habits. Remember bridges and overpasses will freeze first even in temperatures above or near the freezing mark due to the effects of wind chill. Plan to take extra time to and from the job site.

Jan 1, 2004

By Raymond J. Pichette

"Aeromagnetic data can be useful in helping to delineate structures and rock types in gold exploration. Magnetic anomalies associated with Archean volcanic belts in northeastern Ontario can be quickly and effectively analyzed in profile form with the use of model curves. The model curves help to locate contacts between strata. They also help to estimate the magnetite content of the rocks and their depth beneath overburden.An aeromagnetic map of part of Catharine Township, Ontario has been analyzed with the aid of model curves. Several magnetic rock types, potential fault zones and areas of relatively thick overburden were delineated.IntroductionIn any exploration program, a good understanding of the stratigraphy, rock types and structure enhances the possibility of success. For example, environments which host gold deposits in the Abitibi Volcanic Belt may be characterized as follows (Jensen, 1980; Pyke, 1980):(I) They have major faults, especially as tectonic boundaries between volcanic piles which include mafic and ultramafic rocks and clastic sedimentary rocks or gneisses.(2) They have subvolcanic felsic intrusions.(3) They have extensive carbonitization, with or without carbonate and sulphide-facies iron formation.In all cases, delineation of structure and rock type should be a major objective in exploration. The analysis of magnetic data can be a useful tool in this task. This paper is presented with the purpose of describing the application of the magnetic method to gold exploration in Archean volcanic terrains.Magnetic AnalysisTotal-intensity magnetic contour maps can be used to discriminate rock units according to differences in magnetization. However, because of smoothing of texture resulting from the compilation procedure and the fact that survey lines are widely spaced, contours should not be directly used for quantitative analysis. A much more definitive means of magnetic analysis is provided by the use of the original profile or chart recordings. Model curves provide a basis for analyzing these profiles both accurately and rapidly."

Jan 1, 1982

The purpose of this study was to examine the problems of underground coal mining in the United States, and to develop recommendations for an integrated Research and Development Program aimed at resolving these problems. Specific objectives of the study were as follows: ? To identify the existing inadequacies that have adverse effect on Health, Safety, External Environment, and Productivity. ? To identify opportunities for technological advance s to correct these inadequacies. ? To develop an integrated Research and Development Program designed to accomplish the advances identified. Many of the recommended tasks are dearly long range; this is especially true of those for study of future mining systems. However, funding recommendations in this Report are presented for a 5 -year period, since the developments accomplished during this period will undoubtedly be a factor in the formulation of the follow on tasks. Where applicable, the recommended Research and :Development could include development and test of pilot model equipment.

Jan 1, 1970

By A. T. Iannacchione

Underground mining of stone in the US is increasing, as is the depth of overburden above the mines. Data gathered from mine visits, maps, discussion with operators and numerical simulation have been used to investigate pillar design and recommend safe practice. Many pillars have slender shapes with relatively large adjacent mine openings: width-to-height ratios range from 0.54 to 3.13 and extraction ratios from 0.56 to 0.91. The pillar material is often very strong and average overburden only 80 m, but occasional failure due to excessive local stress has occurred where pillar size had been unintentionally reduced, overburdens were greater than 200 m, width-to-height ratios were less than 1.25 or extraction ratios were greater than 0.83. Pillars with width-to-height ratios of less than 1.5 appear more likely to fail under excessive stress. When width-to-height ratios fall below 1.0, defects such as through-running discontinuities can have a significant influence on stability. Dip, orientation and material properties are also important

Jun 21, 1905

By R. N. Johnson

This report is a summary of the work performed for the Bureau of Mines to evaluate the feasibility and desirability of a movable in-pit crusher combined with conveyors to substantially reduce or eliminate truck or train haulage in large open-pit non-fuel mineral mines. The report includes an introduction and summary of previous work, an analysis of movable crusher system components, a description of the selected system, a review of possible movable crusher system applications, and finally requirements for future work to bring about the general availability of such systems. It was clear from the program that there is a real need for movable in-pit crushers.

Jan 1, 1982

By George W. Bain

Summary During the last three years the discovery of gold in the belt of volcanic and sedimentary rocks extending eastward from the Porcupine and Kirkland Lake gold-fields has caused a great deal of excitement in mining circles. The area is heavily drift covered, and every aid to the location of veins is eagerly grasped. A knowledge of the physiographic history of the area is of the utmost importance in the application of many of these aids. Evidence is presented to show that glacial erosion has lowered the general elevation very little below the pre-glacial level, and that many glacial erratics have been carried less than three miles southward. Probably a knowledge of the general geology of a: region was never more necessary to the understanding of the distribution and continuation in depth of the mineral veins than in this area. Four distinct granites occur in the region, and gold-bearing veins are genetically associated with only one of these. Two types of quartz-feldspar porphyries have been found, only one of which has any bearing on the locus of the mineral veins. Many other examples of this complexity of associations might be cited, but everyone goes to show that in most cases the economic importance of the deposits can be realized only after the regional geology is understood. A series of sandstone, limestone and shale intruded by granite lies unconformably below the Keewatin lavas. The latter are intruded by a gneissoid granite and are overlain unconformably by the thick series of Timiskaming greywackes and silts. These are intruded by carbonated syenites and syenite porphyries which have since been rendered somewhat schistose.

Jan 1, 1927

By P. R. Stephenson

"The Australasian Code for Reporting of Mineral Resources and Ore Reserves (JORC Code) has been operating successfully for 14 years, and has an ancestry dating back over 30 years. Together with complementary developments in stock exchange listing rules, the Code has brought about substantially improved standards of public reporting by Australasian mining and exploration companies. The Code is regarded as a world leader in its field, and has been used as a basis for the development of resource/reserve reporting standards in other countries. The reasons for its success are varied, foremost among them being its adoption in full by the Australian and New Zealand stock exchanges, and the ability and willingness of mining industry organizations to bring Competent Persons to account when necessary.The latest revision of the JORC Code was undertaken in 2002-2003, based in part on releases of upgraded reporting standards in Canada, the United Kingdom/Western Europe, and South Africa, and the 2003 edition is expected to be released mid-year. Two of the more significant changes are: the introduction of a requirement for a Competent Person to be responsible for the documentation upon which Exploration Results are reported; and inclusion in the definition of a Competent Person of a reference to “Recognized Overseas Professional Organizations” being overseas professional organizations to which Competent Persons may belong for the purpose of preparing documentation for the submission of reports to the Australian Stock Exchange."

Jan 1, 2004

By J. A. HUFF, V. V. BAKER

This circular is intended to present in brief form the statutory provisions of Pennsylvania regarding mining operations, in force at the end of the 1931 session of the legislature. lo reference is made to general laws which affect mining only incidentally in common with other subjects, such as the workmens compensation law. The statements have been condensed as far as practicable, and provisions not deemed of general interest, such as matters dealing only with administrative details, have been omitted. This circular obviously is not written with such particularity as to be of great value to the legal profession, but it is hoped that it will be beneficial to the mining industry in giving this information in a relatively compact form. At the end of each paragraph the statute from which it is derived is cited to facilitate reference to the text of the law. It is planned to publish additional circulars from time to time dealing with the mining laws of other States. Any criticisms of the form of publica- tion followed herein, or suggestions aimed at the improvement of future circulars, will be welcomed.

Nov 1, 1932

By A. M. Tunstall

Aspects of blast vibrations, damage mechanisms and the influence of rock quality on damage severity are reviewed and results presented from a monitoring programme in which the rock mass rating for six tunnels was determined. The peak particle velocity induced in the tunnels during open-pit blasting was measured and the tunnels were inspected visually for fresh damage after each blast. The results suggest that the quality of rock in which an excavation is situated has an influence on the level of ground vibration to which it can be subjected without sustaining damage. This means that the use of a single limiting value of peak particle velocity, as in the blast damage criteria for residential structures, is not ideal and may result in damage to excavations in poorer-quality rock masses

Jun 19, 1905