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By C. A. Rowland

The use of the Bond Work Index to size industrial grinding equipment is well known. Its use to measure grinding efficiency was presented by C.A. Rowland, Jr. at an AIME meeting in 1976. However, due to a bureaucratic error, the paper was never submitted for publication. This metric has nevertheless been adopted by industry as a widely used standard. The purpose of this paper is to re-present and update the application of this tool as a standard for measuring grinding circuit efficiency. Definition ?standard, n. something established for use as a rule or basis of comparison in measuring or judging capacity, content, extent, value, quality, etc.; as standards of weight and measure? (Webster, 1958).

Jan 1, 2008

By . A. J. Erickson

The Park City District, one of three major mining districts in Utah, is located approximately 20 miles southeast of Salt Lake City on the eastern slope of the Wasatch Mountains. The district has been in near continuous production since 1869. Production has been sustained from exceptionally long bedded replacement ore bodies in the Thaynes, Park City, and Humbug formations and also from several major veins. District production is summarized below. TABLE NO. 1 Park City District, Total Production, 1869 thru 1968 (Source r Various Company Records) [ ]

Jan 1, 1970

By Harry K. Ihrig

The hot-working of iron and steel is an art dating back to antiquity, but until about 25 years ago, relatively few alloying elements were used, and these were present only in small percentages. With the exception of sulphur, the amounts of other elements in steels did not markedly affect their hot-workability. The references in the literature on the effect of other elements on the hot-workability of steel are usually reports of failure of these steels in forging or rolling.1-8 With the increased use of alloying elements, and their use in larger amounts, it was observed that many of the new steels were red short in certain critical ranges or at all hot-working temperatures. The stainless steels are particularly difficult to hot-work. The determining of the correct conditions for piercing, rolling and forging of these alloys by experimentation in the mill often results in large losses of these expensive metals. It also is found that the hot-workability limits of many types vary from heat to heat, and hence poor results are obtained on changing to a new heat after a previous one has rolled satisfactorily. To determine the effect on hot-workability of iron to which various elements have been added, it was necessary to devise a method that could be used on small quantities of metal. In such a method, the minimum number of variables should be present, and the procedure should be simple, quick and correlatable with large-scale hot-working operations. Sauveur,9 in the first Henry Marion Howe lecture in 1924, described the effect of carbon on the ductility of steels in torsion near their critical points. He found that carbon increases the plasticity of gamma iron. In the 1930 Campbell Memorial lecture,10 he gives the effect of carbon, chromium, and chromium and nickel on the ductility of steels under 2000°F. in torsion. Ellis11 has studied the malleability of steels at various elevated temperatures by means of a single-blow drop-hammer test. In this test the percentage decrease in height of standard cylinders is taken as a measure of their malleability. He has shown that in the low-alloy steels studied, carbon has a greater effect than nickel, chromium and vanadium. In 1938 the first tests were run on a new quantitative hot-workability test in the laboratories of the Globe Steel Tubes CO. Thum12 mentioned it in 1940. An illustration of the apparatus was published in January 1942.'' The effect of a few alloying elements on the hot-workability of metals was shown in a description of the test in 1944.14 Description of Test Method The method adopted after a trial of several others is a rapid twisting of bars to failure in a furnace. The standard-size bar was chosen as 9/16 in. It is prepared from larger pieces by forging and cold-

Jan 1, 1947

By Jong-Shin Chang

The Onsan smelter has tried to do various activities to decrease operation costs. With several expansion projects, the Onsan smelter has aimed at not only a quantitative growth but also qualitative growth through efforts improving operations equipment and processes. Activities to reduce operation costs have been one of those efforts. In particular, the energy cost of operation has been a main target for reduction. The activities to save energy have been carried out in two ways. One is to recover and utilize waste heat as much as possible and another is to replace existing equipment and processes with more energy-efficient ones. This paper reviews recent improvements and future plans for energy saving activities at the Onsan smelter.

Jan 1, 2006

By Wm. Reisz

There is no universal standard for Standard Operating Procedures (SOP’s). Every blasting operation has its own unique circumstances, its own methodologies and its own unique demands. It would be nearly impossible to create a one-size-fits-all document that would be totally appropriate for every blasting scenario. But there are universal objectives that should be adopted in any set of blasting SOP’s.

Jan 1, 2010

By G. Ferrara

Hydrocyclones and other dynamic separators are normally fed with pulps of water and solid particles. The particles have different sizes, shapes and densities and, except in the special case of mono-characteristic particles, are segregated into size, shape and density. Segregation is magnified by the high values of centrifugal acceleration in the hydrocyclones. This paper develops the theory of the segregation, indicates the major variables involved and reports experimental data of segregation under different operating conditions for mixtures of magnetite and/or ferrosilicon and non-magnetic minerals.

Jan 1, 1995

By T. Fujita

A high-grade fluorite ore is converted into hydrogen fluoride to produce many kinds of materials containing fluorine. Recently, it is becoming necessary to use low-grade fluorite ore due to the depletion of high grade ore. The low-grade fluorites usually have impurities such as SiO2, P, CaCO3 and arsenic. The most impurities such as SiO2, CaCO3 and P can be removed by using flotation method. However, the removal of arsenic is difficult, and the arsenic contamination decreases the hydrogen fluoride production percentage. The novel technologies for processing low-grade fluorite ore are urgently needed, in order to lower the arsenic concentration to less than 100 mg/kg. In this study, the removal of arsenic from low-grade fluorite ore has been investigated by means of an autogenous grinding using tower mill in sulfuric acid aqueous solution and 0.3 mm zirconia balls in water. The nano grinding in water can prevent the dissolution of 0.3 mm size zirconia balls as grinding media by sulfuric acid solution. Experimental results showed that the arsenic concentration was reduced from 260 mg/kg to 90 mg/kg and CaF2 recovery reached 90% by this process.

Sep 1, 2012

The Committee on Nominations will welcome from members of the Institute suggestions for the offices which are to be filled by election in February, 1018, and which are as follows: One officer, known as Director and President. Two officers, known as Director and Vice-President. Five officers, known as Director. The attention of members is called to Articles V and. VII of the Constitution, and to By-Law VIII, which reads as follows: "The geographical districts to he considered by the Committee on Nominations shall be as follows, until otherwise ordered by the Board.

Jan 8, 1917

By Brad Murray

Evaluating the performance of a shielded tunnel boring machine (TBM) can be difficult because the ground cannot be observed directly and in relation to the TBM attitude within the excavation. It is difficult to determine whether performance problems are caused by ground loading, steering issues, fine muck packing against the shield, or migration of annular grout around the shield. The Arrowhead Tunnels Project in Southern California uses strain gauges on its shielded hard rock TBMs to detect shield strains early and correlate them with tunneling conditions, thereby increasing the chances that problems will be correctly diagnosed and addressed to optimize TBM performance. The frequent automatic measurement of shield strain has also been valuable by confirming whether remedial methods used to free the machine after stoppages are effective. This paper discusses the qualitative interpretation of characteristic strain patterns on the Arrowhead Tunnels TBM shields and discusses installation details and special considerations for setting up a strain measurement system.

Jan 1, 2008

By M. Evertsson, M. Johansson

"In minerals processing control is vital to increasing performance and output of a plant. Model predictive control (MPC) is one of the most effective control strategies used in process industry. Sbárbaro (Sbárbaro and Del Villar, 2010), Asbjörnsson (Asbjörnsson, 2015), and Légaré (Légaré et al., 2016) have for example highlighted the possibility to simulate, develop and tune control systems using plant simulators within minerals processing. In more recent years the use of model predictive controllers have increased, and many process industries now utilize more advanced control methods to regulate their processes, raising the question regarding how to, build, test and verify a proposed control solution successfully. In this research, a linear model predictive controller is formulated and applied to a simulator of an existing tertiary crushing circuit. The circuit has in previous work by Johansson (Johansson, 2017) been modeled in MATLAB Simulink and calibrated relative plant data to an average error of less than 10% over 8 hours of production. The work demonstrates how to formulate the controller model structure to describe conveyor belts, storage components, screens, crushers, and control objectives for a minerals processing circuit. The work illustrates how to apply and successfully evaluate possible upsides in a circuit. The advantage of a crushing circuit simulator is that it can be configured, tuned and modified in any possible way, which is of great benefit to developers and engineers. Additionally, examples of how to use estimated measures to improve the performance of the plant are demonstrated. The control performance is finally evaluated for three different controller configurations."

Jan 1, 2018

The South Wall Base Case Design for Mt Whaleback indicated that along portion of the South Wall a cigar shaped synclinal keel, contain- ing 14 800 m', of Dales Gorge Member ore, would be unkeyed and bed- ding undercut. The dry "ore lobe" slope would be 60m high, unbenched and approximately 170 m long. Stability analyses using specific design parameters established that artificial reinforcement could stabilise the slope and be economically justifiable. To implement the slope design reinforcement for such a complex geo- logical structure it was necessary that all functions pertaining to slope excavation be integrated and co-ordinated within the Mine Geotechnical Section. The objective being to minimise slope damage and thereby optimise the effect of design reinforcement. The successful excavation of the ore lobe in 1988, three years after the introduction of artificial reinforcement, was achieved by strictly main- taining the following parameters. 1. Accurate Geological Model 2. Controlled Perimeter Blasting 3. Controlled Excavation Techniques 4. Quality control -Reinforcement Installation 5. Additional Reinforcement.

Jan 1, 1989

By George R. St. Pierre

A method for the quantitative description of activity interactions between solutes in a metallic solvent which is consistent with stalistical thermodynamic principles is presented. The chemical potential of a solute in an alloy is derived from the weighted mean of its values in the individual solvent components, µi = S?jµi(i). The weighting factors, ?j, are obtained from the distribution functions. The resulting equation contains far fewer adjustable parameters than the Epsilon Formalism and because of its correct functional form it provides an improved fit to the available data on a variety of alloy systems containing oxygen, carbon, sulfur, nitrogen, and hydrogen. For a binary metallic solvent ( A, B ) containing a solute (i), it is shown that

Jan 1, 1995

By Travis Q. Lyday

Mineral production in Fiji, a group of 322 volcanic islands and atolls of Melanesia in the southern Pacific Ocean, continued to be dominated by gold. However, the Fijian mineral sector remained a minor factor as a source of export earnings, Government revenues, and employment, generating only 1% of the gross domestic product (GDP), estimated as $1.2 billion.2 The largest and most important mining operation was the Vatukoula gold mine on the north side of Viti Levu, the main island. The Vatukoula Mine has been in prduction since 1932, producing about 3.8 million troy ounces of gold and 1.3 million troy ounces of silver to date. In April 1983, the large Australian mining firm, Western Mining Corp. (WMC), assumed operation of the mine in a joint venture with Emperor Gold Mining Co. Ltd., which operated the mine previously. The WMC takeover of the mine management was expected to bring in additional capital and technological expertise in order to modernize operations, increasing both efficiency and output. During the year, rate of recovery was only about 75% of the gold contained in the ore and only 40% of the contained silver. Mining at the Vatukoula Mine was done using bath opencut and underground methods, with about 60% of the ore mined attributed to the underground operations.

Jan 1, 1985

By L. R. Burdick

Sulfur compounds have long been recognized as damaging pollutants of the air. A number of investigations have been made to determine the amount of such compounds existing in the air of various cities; moreover, some study has been given to the conditions affecting the concentrations. This paper summarizes published investigation and includes a bibliography on the subject. The methods of obtaining data have differed to the type of sampling, analysis procedure, hour of sampling, number of locations, and number of determinations made. Sampling methods include both the continuous type, covering a day or a number of days, and what can considered the ?snap? type, covering very short periods. Continuous sampling has, given data representing the average concentration at the location chosen but no information regarding variations from hour to hour, are none that might be said to represent the average for a city. The snap-sampling method, while not giving a true average for any one location or area, has in some instances made available date regarding variations of concentration during different hours of the day and at various locations or zones within the area chosen. Although the sulfur compounds in the air nay include sulfur dioxide, sulfur trioxide, hydrogen sulfide, and organic compounds of sulfur, most investigators report on the basis of sulfur dioxide. This gas unites with moisture to form sulfurous acid.

Jan 1, 1939

By Raj K. Rajamani, Poly K. Songfack

The slurry transport within the ball mill greatly influences the mill holdup, residence time, breakage rate, and hence the power draw and the particle size distribution of the mill product. However, residence-time distribution and holdup in industrial mills could not be predicted a priori. Indeed, it is impossible to determine the slurry loading in continuously operating mills by direct measurement, especially in industrial mills. In this paper, the slurry transport problem is solved using the principles of fluid mechanics. First, the motion of the ball charge and its expansion are predicted by a technique called discrete element method. Then the slurry flow through the porous ball charge is tackled with a fluid-flow technique called the marker and cell method. This may be the only numerical technique capable of tracking the slurry- free surface as it fluctuates with the motion of the ball charge. The result is a prediction of the slurry profile in both the radial and axial directions. Hence, it leads to the detailed description of slurry mass and ball charge within the mill. The model predictions are verified with pilot-scale experimental work. This novel approach based on the physics of fluid flow is devoid of any empiricism. It is shown that the holdup of industrial mills at a given feed percent solids can be predicted successfully.

Jan 1, 1995

New York Meets first Wednesday after first Tuesday of each month. DAVID' H. BROWNE, Chairman. JOHN H. JANE WAY, Vice-Chairman. F. E. PIERCE, Secretary, 35 Nassau St., New York, N. Y. P. A. MOSMAN, Treasurer. LEWIS W. FRANCIS. BENJAMIN B. LAWRENCE. Boston Meets first Monday of each winter month. HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman. HENRY A. WENTWORTH, Secretary-Treasurer, 60 India St., Boston, Mass. A. H. EUSTIS, F. G. STANTIAL. Columbia Holds four sessions during year. Annual meeting in September or October. STANLY A. EASTON. Chairman. FREDERIC KEFFER, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash.

Jan 3, 1916

By A. Klingberg, M. Svensson, N. Smolko Schwarzmayr

"Removal of silicates and carbonates from sedimentary phosphate ores by the use of new synthetic collector/formulations was investigated in a comparative study with traditionally used collector systems as references. In the direct carbonate flotation the new formulations showed higher efficiency, contributed to an improved balance of P2O5 recovery and P2O5 enrichment in the recovered material. Efficiency of the new formulations containing synthetic surfactants was 1.5–2 times better than potassium salt of fatty acid sulfonate based formulations that are traditionally used for that purpose. The new formulations also provided up to 7% increase in P2O5 recovery at the same P2O5 grade. The new synthetic collectors for removal of silicates showed extremely good selectivity towards silica bearing minerals. The selectivity factor for the flotation tests when new formulations were used was 32–52 and for the flotation tests with the traditional collectors: 20–32. The ratio between distribution of an amount of silicates (as SiO2) and distribution of phosphate in the froth (waste) is defined as the selectivity factor. The new formulations provided more than 2% decrease of the amount of SiO2 at the same P2O5 recovery.INTRODUCTIONPopulation growth and decrease of arable land are the main reasons for constant increase of consumption of apatite (phosphate ore) in the fertilization field (Lannefors, Gorochovceva, Klingberg, Lima, & Gustafsson, 2015). Fertilizers play a key role for farmers to produce more with less land. The phosphate component of the fertilizer is vital for producing healthy and large amount of crop. As a result the demand for phosphate rock is growing.The largest producers of phosphate rock are the Unites States, Morocco, Tunisia, China, Russia, and Brazil. The term “phosphate ore” includes all phosphate-bearing minerals and rocks, but only two of them are of industrial interest: apatite (igneous origin) and sedimentary phosphate (Peres, Araujo, El-Shall, Zhang, & Abdel-Khalek, 2007). The majority of the world’s phosphate deposits are of the sedimentary type. There are two different types of sedimentary phosphates: siliceous and carbonaceous which are categorized based on gangue minerals (such as quartz, carbonates, mica, and clay)."

Jan 1, 2016

Theoretically mobile primary crushers at the mine working face can be considered the ideal comminution system. A crusher which follows the ore can reduce materials handling costs because it eliminates about one ton of truck deadweight per ton of ore hauled to the crusher. It also eliminates the backhaul of this same deadweight ton. Development of mobile primary crushers has centered in Germany where many soft iron ore and limestone deposits are flat-lying and thus readily adaptable to the use of shiftable conveyors which easily followed the working face. These ores were easily crushed in impact- type mills which had extremely large receiving openings and therefore large reduction ratios. The feeding of such a unit was done with a front-end loader which dumped its load to an inclined apron feeder, which in turn fed the impactor. Under the crusher was an inclined conveyor which transferred the crushed ore to a belt wagon for delivery to the shiftable overland conveyor. Low headroom overhead eccentric single-toggle jaw crushers and short-shaft gyratories were also used on these units, which generally travelled on tracks. While these early mobile primary crushers were versatile and served their purpose, they generally suffered from low capacities. Manufacturers have quickly responded with larger crusher, feeders, and moveable supports, however; and today mobile crusher s have capacities of up to 1500 metric tons per hour, a figure comparable to the capacity of some 54 in. by 74 in. gyratories. An example of a quarry portable crushing plant is at the Bath cement plant of Canada Cement Lafarge, Limited. Two 12 cu yd front-end loaders are digging the stone and hauling it to the portable crushing plant which feeds a field conveyor system. The crushing plant is moved and the field conveyors extended whenever the length of the haul exceeds 300 ft. At the crushing plant, the loaders discharge the stone onto a pan feeder which feeds into the hopper of a Weserhutte-Hazemag compound crusher which combines primary and secondary rotors in the same housing. These are driven at 1200 rpm by 800 hp and 1,000 hp motors (600 and 750 kw). The maximum 3 ft feed (914 mm) is reduced to 3/4 in. (19 mm) at 800 tph. The Weserhutte steered walking mechanism, operated by hydraulic cylinders, takes five -foot strides. Another example is at Alcoa of Australia's operation at Huntley in Western Australia. At the mine face, front-end loaders load 50 mt rear-dump trucks that transport the bauxite ore to the mobile crusher which follows the mine operation. The crusher can turn 360° within its own length, walk at a speed of 34. 5 ft per minute (10.5 m per

Jan 1, 1978

By T. V. Vasudevan

Floc properties such as density, size, size distribution, porosity, and shear strength govern the effectiveness of flocculation as a process for solid-liquid separation. The floc characteristics desired for removal of suspended solids by sedimentation or filtration, for example, are known to he different. In this study, an attempt has been made to evaluate the effects of various physical and chemical factors on the density and shear strength of the flocs.

Jan 1, 1990

A. H. Mokken: I am pleased to have been given this opportunity to make a contribution to Dr Muller's paper tonight. The reason for this is that, at one stage in our careers, we were associates in the same undertaking. Dr Muller, then fresh from University, with a degree in pure science, had just stepped onto the first rung of the ladder, which, it was then thought, would lead him to a career in gold extractive metallurgy. However, endowed with an enquiring mind and conscious of a lack of fundamental training in general metallurgy and engineering, he felt a need for further academic study. To meet this need and, more importantly, to meet the necessary finances, he found his opportunity in steel. Armed with a bursary, he bade farewell to gold and proceeded overseas, to the University of Sheffield, to train as a steel metallurgist. The outcome of these academic efforts, which were followed by assignments in the steel industry and a further period at Sheffield, is the man we have listened to tonight-a highly qualified metallurgist who has displayed a sound knowledge of his subject. In choosing Sheffield, Dr Muller became associated with a steelmaking centre of world renown, a centre usually credited with the first systematic production of alloy steels, as far back as the 18th century. Since that time, great advances have been made in the production of alloy steels and this is especially so in the last decade or two, when major developments in civil, mechanical, electrical, aeronautical and nuclear engineering have been made possible by the development of steels with improved properties. In spite of spectacular advances in the technology of non-ferrous alloys, plastics and other materials of construction, steel has maintained its role as a pre-eminent material for engineering use. With the gradual accumulation of data on the properties of steels, and the use of thin film electron microscopy, to study the behaviour and characteristics of such phenomena as dislocations in metals and other microstructural features, the physical metallurgist appears to be approaching the stage of an exact understanding of such phenomena as strength, ductility and brittleness-a knowledge which could lead to close control of such properties and, therefore, to the attainment of the highest goals. An interesting example, illustrating the use of fundamental principles, based on physico-metallurgical research, is the development of the maraging steels developed by Bieber at the International Nickel Company. These steels have met the extreme technological requirements of the space age by providing the material for the cases of large rockets in which qualities, such as high tensile strength, toughness, workability and weldability are most important. Attractive as they might appear to be in considerations of savings of weight, cost of erection, transport of materials and foundations, the use of high strength steels has been accompanied by special problems such as brittle fracture, hydrogen embrittlement, notch-toughness and fatigue. It has been found that high strength steels, which performed acceptably in conventional tension tests, were found to undergo failure, in a brittle manner, in service. Hydrogen embrittlement has caused spectacular failures at a fraction of the normal ultimate tensile strength, and a lack of correlation between fatigue and tensile strengths has diminished the advantages to be obtained from the use of high strength steel in some applications. A new approach to the selection of materials for engineering design has resulted from a consideration of these phenomena in which strength, as such, is no longer as significant as it was previously. Parallel with the development of high strength steel has been the need for suitable techniques for joining component parts and here welding has played an