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By D. A. Dahlstrom

Crushing and grinding consumes about 1.3% of the nations produced electrical energy.( Furthermore, only one in the first ten highest consumers comes from an industry other than mineral processing. This is the grinding of wheat to make flour. The other nine are all in the metallurgical industry and are easily the largest consumers.

Jan 1, 1988

By H. Lyn Bourne

The is the 13th year for this column and the 12th in which the royalty data have been tabulated. There still exist some holes in the list of royalties that readers hopefully will fill. The most common mineral commodity is construction aggregates - either sand and gravel or crushed stone. In spite of their pervasive use nationwide, there are states from which the author has no information about royalties for either of these commodities. The reader can help - share information about these missing states and next year there will be fewer states without information. Severn Brown again sends helpful information from the Prospectors and Developers Association of Canada (PDAC). The PDAC Digest contained an article that distinguished between ‘net smelter return royalty' and ‘net profits royalty’ (Haase). The article also lists clauses and details that Brown suggests should be included in a net profits royalty contract.

Jan 1, 1994

By Jida Wu, Zhenqian Wang, Chusheng Liu, Wenqiang Qiu, Mengqi Zou, Wei Zhao

During the dry screening, the hole plugging is a serious problem for most traditional screening equipment sieving the moist fine coal. It would lead to the low preparation efficiency and the low screening efficiency. The flip-flow screen is a new kind of screening equipment by using flip-flow motion of elastic screen surfaces to implement the separation of material. With the remarkable advantages of the extraordinary vibration intensity of screen surface, the hole is difficult to be plugged, and the screening efficiency is improved. In this paper, a kind of centralized forced flip-flow screen (CFFS) was proposed based on the crank rocker mechanism. The flip-flow motion of elastic screen surfaces is achieved by the periodical reversed motion of inner and outer screen boxes driven by crank. The advantages of the CFFS include considerable deformation of the screen surface, stable flip-flow quantity, low working noise, low vibration influence on environment, etc. The principle and construction of the CFFS were introduced, and the modal analysis and harmonic response analysis of key components (the crank and the linkage) were implemented based on finite element method (FEM), respectively. The first six orders of natural frequency and vibration modes were obtained. The maximum equivalent stress and strain under working and resonance frequency were achieved. The results illustrate that the resonance frequency is much higher than the working frequency, and the stress and strain are all within the safe limit of the material. The prototype was manufactured, and the sieving experiment demonstrates that the CFFS perform steadily, and screening efficiency is over 80%. The new feasible method of the dry screening was proposed by the CFFS. The corresponding numerical simulation and the experiment provided a reliable basis for the future promotion of similar product design and research.

Jan 1, 2017

By Eldon L. Abbott, Rebecca K. Bolan

The Florida Department of Transportation, Florida’s Turnpike Enterprise is studying the feasibility of a 1128 meter (3,700 foot) vehicular tunnel to provide direct access for Port of Miami traffic to/from I-395, I-95, SR-836 (Dolphin Expressway) and Miami International Airport. Both Bored and Immersed Tube tunnels were evaluated and re-evaluated for constructing two, two-lane, 11.9 meter (39-foot) diameter tunnels beneath the Main Shipping Channel lying between Watson Island and the Port of Miami on Dodge Island in Biscayne Bay, Miami, Florida, USA. Bedrock Geology of South Florida is predominately very permeable, vuggy limestone with sand seams and occasional voids. Groundwater inflows in deep cut-and-cover excavations, tunnel buoyancy, grouting, maintenance of Port operations and potential/possible environmental impacts to Biscayne Bay were significant issues.

Jan 1, 2005

By S. A. Pirzada

A thermal plasma assisted laminar flow reactor has been used to evaluate the kinetics of converting alumina to sodium aluminate in flight. Free energy minimization calculations were used to determine experimental conditions. The experimental variables include: alumina particle size, alumina/sodium nitrate molar ratio, temperature and residence time. A mathematical model for the conversion was developed and validated. Experimental and mathematical results are presented.

Jan 1, 1996

By G. P. Hand

Graphite usage in the United States during 1994 was fairly strong. The hearty showing of the domestic economy, along with sound performances from the major industries that use graphite, helped make 1994 a solid year for the graphite industry. Supply Virtually all natural graphite is imported into the United States, as there is no domestic production. The primary producers are Brazil, Canada, China, Madagascar, Mexico, Mozambique, Sri Lanka and Zimbabwe. Mozambique is a new producer. It is now supplying a high-carbon, large-crystallite flake in large quantities. Sri Lanka continues to experience problems with one of its two mines, closing operations in December 1994. The synthetic graphite used domestically was produced primarily in the United States as a byproduct of electrode production. Synthetic graphite was also imported from Switzerland for specialized applications. The purified graphites/carbons, such as Desulco and ThermoPURE materials, were also produced domestically. There was a sufficient supply of all types of graphite to meet domestic demand.

Jan 1, 1995

By A. Mayton

The prolonged exposure of equipment operators to shock and whole-body vibration (WBY) is linked to cumulative back, neck, and abdominal disorders. In low-coal mines, space restrictions make seat suspensions difficult to use in isolating operators from shock and WBY. Researchers at NIOSH, Pittsburgh Research Laboratory, are responding to these issues by investigating viscoelastic foams. For the full-load case. an ergonomic seat with viscoelastic foams isolated the shuttle car operator from shock at 15Hz. Researchers used results from additional foam testing with an analytical model to identify viscoelastic foams that provide shock isolation at a frequency below 5 Hz.

Jan 1, 1998

By S. C. O?Brien

This paper develops the procedure for simulating the special locked-cycle Work Index laboratory test using the kinetic parameters obtained by conducting standard size-mass balance (SMB) grinding tests and presents the results for three materials - quartz, a taconite iron ore and a bituminous coal. It was found that the WI could be determined by simulation; however, if a material breaks abnormally, a full description of its abnormal breakage is necessary. It was also found that the sensitivity of the WI test procedure to the sieving process and the estimating of the 80% passing size of the sieve undersize is sufficient to question the practice of quoting a WI to two or more decimal places. Finally, if a material grinds abnormally in the Work Index mill, then the WI test should not be conducted.

Jan 1, 1987

By Paul A. Gerding

PURPOSE: Presentation to Society of Mining Engineers, Technical Session, Wednesday, February 19, 1958 - 2:00 P.M. General Industral Minerals - Penn Top South The silica industry is relatively small and in general is made up of small plants located near the consumer. In the United States there are approximately 155 established operating plants located in 37 states, extending from coast to coast. Silica, in varying degrees of chemical purity, enjoys a very diversified market. Silica is the basic ingredient of glass, bothcontainer and flat glass, and is used for grinding and polishing of flat glass up to the final polishing stages where rouge is generally used. Silica is used for foundry molds and cores, sandblasting, stone cutting, refractories, placing sand in furances, glass coatings and linings, laboratory glassware, construction, oil well fracturing for increased oil flow, filtering purposes, silicate of soda, silicon carbide, and others.

Jan 1, 1958

By R. Michael Craig

The flood basalts of the Columbia Plateau in eastern Washington State are under investigation for suitability in siting a deep geologic repository for high-level radioactive waste. To support safety and feasibility evaluations of the proposed repository construction and operation, an assessment is necessary of the potential for inflow of groundwater to the repository excavations from the surrounding saturated rock. Preliminary estimates of inflow are presented using simple models appropriate to the current understanding of available data. Both normal and bounding analyses are presented.

Jan 1, 1986

By R. Elias

Botswana is a mining-dominated sub-Saharan country. Workforces are characterised by poorly educated operators and front line supervisors, with equipment and management to 1st World standards. Poor communication, ignorance of business objectives, inability to meet targets, and lack of problem-solving capacity are the norm. Training leads to high expectations and is of concern to management as a source of dissatisfaction, despite the long-term benefits higher skills have for mine viability. The aims of a technical training programme are presented with various models and approaches being implemented at operations in Botswana. These are used to construct a series of guidelines for technical training initiatives.

Jan 1, 2000

By J. F. McDonald

On December 8th of last year, the new St. Clair River tunnel was holed-through to Port Huron, Michigan. The tunnel, commissioned by the Canadian National Railway, was needed to replace an existing tunnel that had been built between 1889 and 1890, and had remained in continuous operation until the new tunnel was opened to traffic in April of this year. The original tunnel, after more than 100 years of service, was still structurally sound, but was too small to accommodate the double stacked container cars and other advances in the railroad's equipment that had developed over the years. Prior to the construction of the first tunnel, all freight was barged across the river. It was a slow, expensive process, which in winter was sometimes impossible. The nineteenth century tunnel was built in twenty months, utilizing two shields that mined to the middle from each end. The lining, which is still in excellent condition, consisted of bolted, cast iron segments, with an O.D. of 6.4 meters. It was the first sub-aqueous tunnel built in North American, and it's use of compressed air under the river and hydraulic power on the shields may also have been firsts. The digging was done by hand, and the muck hauled out by mule drawn wagons. Boulders and methane gas were reported to be a constant problem during the drive, and compressed air sickness was common, but when the two shields came together in August of 1890, it was reported that the alignment was within 6 mm. The new St. Clair River Tunnel was constructed for basically the same reason as the original. The larger equipment which the railroad is using today would not fit through the old tunnel, and once more they were forced to ferry the cars across the river.

Jan 1, 1995

By G. Gaidajis, K. Angelakoglou

The development of a tool for assessing the environmental sustainability of mining facilities is described in this study. The tool is based on the analysis of basic components of the examined system, i.e., the quantities of the incoming materials and outgoing wastes, their hazardousness and scarcity, the utilization of water and energy resources, and the biodiversity. The developed tool provides both qualitative and quantitative assessment of the environmental performance of a mining facility in a broad time scales (past-present-future) and is easily applicable from non environmental experts. Moreover, relative software is developed to further support the application of the methodology. The implementation of the tool is expected to lead to an improved understanding of the environmental performance of a mining facility and more importantly identify the areas of significant environmental concern. However, based on feedback from industries, a number of shortcomings of the approach have been identified so far and are presented, indicating further actions for the advancement of the proposed tool.

Jan 1, 2011

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. An alternative parameter, the organic efficiency, does indirectly consider process economics, but it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach, the partition moment of inertia, is introduced. This parameter reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure that promises better use of performance data. IntroductionPartition curves are commonly used in the characterization, evaluation and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, density separators and other beneficiation technologies that are based on intensive physical properties. Graphically, the partition curve depicts the recovery of particles as a function of the physical property on which the separation is based, such as particle density, size or magnetic susceptibility. Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic S shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout, or bypass, values; the midpoint slope; and the separation cut point, defined as the property value with 50 percent recovery.Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, as a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point, that is, an infinitely large slope. One common formulation of this slope, the Ecart Probable, Ep, is derived by evaluating the slope between the 25 and 75 percent recovery points:"

Jan 1, 2016

By Tan Zhenxiang

INTRODUCTION Koolyanobbing is an open cut iron ore mine, which is located in Yilgarn region of Western Australia. To prevent the operators from suffering silicosis diseases and protect the air from being polluted, a series of dust control measures have been taken. These measures include ventilation and dust control system for sample preparation shed, dust collecting system for drill rig, dust suppression system for ore processing plant, dust control for haul road. The details related to individual dust control measure are dealt as follows. SAMPLE PREPARATION SHED DUST CONTROL The sample preparation is one of the major dust sources at Koolyanobbing. The activity is being carried out at the sample preparation shed. It typically needs to go through the following stages, that is, crushing, splitting, drying and pulverising. The amount of dust generated from crushing and splitting is mainly determined by the moisture content contained in the pre- pared sample. A significant amount of dust is generated at the sample pulverising stage due to cleaning sample bowl with com- pressed air. To protect the sample preparing personnel's health and make the dust level in the air meet the requirement from the health and safety authority, a central ventilation and dust control system has been installed at the sample preparation shed. As shown in Fig. l, the system consists of suction heads, suction lines, dust collector and vacuum fan. The fan creates vacuum environment in the system, therefore the dust is drawn into the dust collector through the suction heads and suction lines. The dust collector is of fabric filter. When the dusty air comes to the filter, the dust in the air is collected and retained on the surface of the filter while the clean air passes through and enters the atmosphere. The retained dust is blowed out by the pressured air pulses and deposits into the dust bin underneath the filter. A time relay device is used to control the cleaning time and the cleaning interval. DRILL RIG DUST CONTROL A hydraulic percussion drill is used to drill blast holes. To carry out the drilling operation properly and efficiently, the cut- tings are being flushed out of the hole by the compressed air. In order to prevent from the fine particles in the cuttings escaping to the air, a dust collector is attached to the drill. The collector mainly consists of suction head, cyclone and bag filter. Refer to Fig. 2. The suction head is installed at the lower end of the feed beams and is movable. The moving range is up to 250 mm. It is not only used to restrict the cuttings, but also used to prevent water from entering the filters when drilling wet hole. A 406 mm diameter primary cyclone is used to separate the heaviest particles in the cuttings. It is also used as blast holes sampling equipment. One part of the dust particles are collected by a sample bag through a splitter attached to the end of the cy- clone. The rest of the particles fall down to the ground through the closing rubber. The bag filter is driven by a hydraulic motor (1). It is used to collect the lighter particles in the cuttings. The filtering area is 16 m2 and the dust separation efficiency is up to 99.9%. The working principle of the filter is demonstrated in Fig. 3. When the rock drill (9) flushing is turned on, the pressurised air from the compressor is directed to the rock drill and to the pres- sure switch (10). The pressured air will open the pressure switch to de-energise and close the solenoid valve (4) The pressure affecting the cut-off cylinder (5) keeps the exhaust port flap open. When the flushing valve (8) is closed, the pressure affecting the cut-off cylinder disappears and the internal intake opening flap is closed by a spring. The pressure also ceases to affect the pressure switch and the spring switches the contact to the point 2. The time relay (11) is now activated and gives a 0.5 second current impulse to the solenoid valve and keeps the current cut off for approx 8 seconds. When the solenoid valve is live, it opens and lets an impulse of pressured air to the filters (2). These impulses will clean the filters.

Jan 1, 1997

By P. Rambalee

A multiple coal fired boiler house provides steam for utility usage in various production plants. Maintaining stable header pressure and boiler availability is of critical importance for downstream consumers. Advanced Process Control comprising of a G2 based expert system and Model Predictive Control was implemented to improve the boiler house performance. The results yielded improvements in the main header pressure stability, reduction in boiler saturation and significant saving in coal consumption. All information used for this document is from a published whitepaper written and led by Prevlen Rambalee (Anglo Platinum) and Gustaf Gous (BluESP) titled, ?Control and Stabilization of a Multiple Boiler Plant: An APC Approach?.

Jan 1, 2012

The dissolution behavior of gold and silver from Au/Ag alloys in aerated cyanide solutions has been investigated using rotating disc electrodes. The variables studied included concentration of cyanide, oxygen partial pressure and rotating speed of the disc. The dissolution potential and the rate of dissolution were obtained in view of the anodic and cathodic current-potential relationships. The results were discussed in terms of a mixed potential theory. The results showed that the dissolution rate of gold and silver from the alloys was partially controlled by chemical reaction, but largely by transport of either oxygen or cyanide, depending on their relative concentration under the experimental conditions employed in this study.

Jan 1, 1995

By Frederick C. Moore

This paper describes the original planning which actually resulted in the opening of a new aggregate plant located in central New York State. This plant, which is now named the Skaneateles Plant of The General Crushed Stone Company is unique in that the plant itself is a departure not only in design but in concept of operation from the normal aggregate plant the company has operated in the past. Whether or not the concepts which resulted in the Skaneateles Plant are economically feasible remain to be proven by the next few years of operation. By way of background data about our company which will help set the stage for this presentation, we currently operate seventeen stone quarries in the states of New York, Pennsylvania and Virginia. These quarries range in size from 200,000 tons per year to 1,500,000 tons per year with a total annual stone production of approximately 7,500,000 tons. We also produce about 1,250,000 tons of sand and gravel at six sand and gravel plants, 300,000 cubic yards of ready mix concrete, 1,500,000 tons of bituminous concrete, aglime and other minor construction materials. In many cases we are our own best customer consuming a large percentage of the total production of our own aggregates in our various ready mix and blacktop plants. Up to the concept of the Skaneateles Plant our operating facilities have been of the permanent type as opposed to the moveable or portable type plant. The steps involved in the case history of Skaneateles will begin with the basic economic requirements, market research, geologic surveys, land acquisition, zoning and financing and carry through to the final design and construction. We will attempt to show what some of the problems were, how we interpretted them and how we proceeded to solve them. The current results are apparent and can be analysed. The success of the total concepts of the Skaneateles Plant remains for future analysis.

Jan 1, 1968

By J. Carr

Ring gear and pinions used as the final drive on large metallurgical grinding mills are expected to transmit their rated horsepower reliably for long periods of time. Duty is 24 hrs./ day. Life expectancy of such gear sets is of the order of 20 years; that is, each gear and pinion flank is expected to resist failure by pitting for 10 years. This means that for a dual pinion gear set having a ratio of 18.42:1.0 and a mill speed of 10 RPM, every gear tooth will see 105.12 x 106 surface contact stress cycles and every pinion tooth will see 968.15 x 106 surface contact stress cycles in a 10 year period. The allowable surface contact stress on the gear and pinion is determined by the material hardnesses. The rule being the higher the hardness, the higher the allowable surface contact stress may be.

Jan 1, 1985

By Paul A. Rittenhouse

First of all, I want to thank John Dunlap for asking me to this AIME meeting in Denver. I was first introduced to Denver and The Rocky Mountains more than ten years ago and immediately decided it was one of the most attractive spots in the world. I've come back many times since and still welcome any opportunity to return, even if it means I have to prepare and give a paper on potash. When John Dunlap gave me this assignment, he told me that the program would include papers on the geology of potash, papers on new discovered potash deposits and new mines and asked me to discuss potash from the commercial point of view. He also asked me to include a supply/demand outlook for potash. However, one thing he did not mention was "how far into the future he wanted me to look" and it seems to me the time element is a crucial factor to you who are both geologists and miners as well as to me. In your case, you have to look far enough into the future to give you time to explore, find, evaluate, develop, and bring into production a commercial deposit. My mining associates and friends don't agree on how long that takes but it's probably somewhere in the range of eight to fifteen years. But, they all agree on one thing and that is that the time required is continually getting longer. Now my time problem is just the opposite. It is "relatively" easy, and I stress relatively, to identify and evaluate the importance of the various factors that impact on both the supply of and demand for a commodity such as potash if the time period is today. It gets a little tough if one has to project into tomorrow or next week or next month. And when we start talking in terms of a year, five years or ten or fifteen years, things really get sticky and the old crystal ball becomes mighty cloudy. But we economists and forecasters are not known for our temerity so let me get on with the job at hand and take a look at the world potash supply/demand outlook.

Jan 1, 1978