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By V. Srivastava, T. Ghosh

The modeling and simulation of semiautogenous (SAG) mills have been widely used in the design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. 7KLVSDSHUDWWHPSWVWRFKDUDFWHUL]HPLOOFRQWHQWVE\VROYLQJ:KLWHQ¶V¿UVW RUGHUFRQWHQW EDVHGPRGHOLQWKH0$7/$% Simulink environment. The parameters in the model, such as breakage rate constant, discharge rate and appearance function, were estimated using process and design data collected from a gold mine operating in Alaska coupled with a nonlinear parameter estimation scheme. This model was then used to predict the dynamic responses of other key operational variables, such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated using dynamic response data from the plant to encompass operational characteristics of SAG mill behavior.

By L. M. Gochioco

The U.S. coal industry is under-going dramatic changes to meet the challenges of the keenly competitive fuels market. The application of innovative technologies is needed to improve safety and to increase productivity in order to make coal more competitive as a fuel. As more coal companies shift into capital intensive longwall mining, there is a clear need to invest more in exploration before mine plans are made. Coal seam anomalies may create adverse mining conditions. The early detection of these anomalies could make the longwall mining safer and more productive through improved planning. A standard exploratory drilling program can provide only limited geologic information. The seismic reflection technique can be used to detect coal seam anomalies and is effective in reconnaissance surveying. Recent advances in the quality of coal seismic data have increased the success rate of seismic surveying. Therefore, surface seismic surveys, coupled with selective drilling, will come to play an integral role in coal exploration in the 1990s.

Jan 1, 1990

P. H. ARGALL, Magdalena, N. Mex. (written discussion *).-The Chilean mill has generally been considered a fine-crushing machine and as such has had many advocates; it has also. had quite a number of denouncers; hence, the action of the Portland engineers in using the Chilean mill for the preparatory work usually accomplished in, rolls or rock breakers and adding a ball mill to do the fine grinding is novel, though of doubtful utility in the long run, even though a fair efficiency is obtained for the combination machines, as measured by Chilean mill practice. In order to follow the development of Chilean mill practice on Cripple Creek ores, I might say that two 6-ft., Chilean mills were placed in operation in Stratton's Independence mill in April, 1908, treating ore crushed by rolls to pass Y4 in. screen aperture. Screening was, however, found to be an unnecessary refinement, as was also the use of plows in the mills; both screening and plowing were abandoned before the Portland engineers finished the experiments in stamp milling upon which they were then engaged. Two additional 6-ft. Chilean mills were added in the spring of 1911, three of them giving the required 10,000 tons per month capacity, one being always in reserve. The Portland company began using Chilean mills in June, 1910, at its Victor mill, and the same company purchased the Stratton's Independence mill in June, 1915, and remodeled it; it is now known as the Independence mill. A description of Stratton's Independence milling practice, is given in the November, 191.1, issue of Mining Majazine (London). These Chilean mills were used as fine grinders and that they accomplished their purpose is shown by the screen analyses, in which 62 per cent. of the pulp passed 150-mesh screens. To make coarse crushers of these Chilean mills, the Portland engineers have increased the speed, substituted steel in various parts for cast iron, provided new and enlarged thrust bearings to take care of the centrifugal force incident to higher speed, and have, thereby, greatly increased the cost of the machines. They have also reduced the width of the tires and dies from 8 in., as used in the original mill, to 7 in., a reduction of 12 ½ per cent. in the crushing surfaces, to say nothing of the loss of abrasion or attrition incident to the larger surface. At the same time, they have apparently increased the weight of the rollers by using tires 5 7/8 in. thick as against tires varying between 3 and 4 in. on the original mills, thereby increasing

Jan 4, 1920

By Thomas W. Chapman, Shi-Chern Yen, I-Min Lu

"An electric field was applied to a metal-bearing kaolinite specimen to investigate the efficiency of electro-osmosis in removing heavy metals from contaminated soils. The electric field induces a flow of water through the porous medium, called electro-osmosis, which is superimposed on the hydraulic flow. Because the electro-osmotic flow is relatively stronger in smaller pores, it can enhance the displacement of contaminated solution by fluid convection. Furthermore, local changes in pH caused by the electrode reactions can affect adsorption equilibria and the distribution of solutes between the solution and the solid surfaces.The electro-osmosis experiments were conducted by applying either a constant current or a constant voltage across 8-cm inside diameter, 25 to 30-cm long specimens of kaolinite clay with graphite electrodes. Samples of the pore fluid and of the clay were analyzed to determine metal content, pH, and conductivity as functions of time and position. Results show that removal of heavy metals from soil can be accomplished effectively by electrokinetic treatment of sufficient duration. Approximately 95% of the lead was removed after 189 days.IntroductionRemediation of soils contaminated with toxic chemicals is a difficult and expensive task. Washing or leaching are not particularly effective if the contaminate is sequestered in small pores; hydraulic flows of water pass through larger pores leaving the smaller pores relatively untouched. Electro-osmosis appears to be the most promising new technology for removing heavy metals and organic substances from contaminated soils (Segal, 1980; Hamed et al., 1991, Masliyah, 1994).Electro-osmosis is one of several electrokinetic phenomena that occur through the interactions among an electric field, fluid motion, solute adsorption, and the existence of a net charge on a solid-fluid interface (Newman, 1991, Masliyah, 1994). Electro-osmosis refers to the fluid flow in a porous medium that results when an electric field acts on the mobile region of the electrical double layer, the solution-side region of charge separation that exists at the pore walls."

Jan 1, 1996

By Hernan Fernandez, Khalid Saif F S Al- Khayareen, Volkan Salepciler, Jacek B. Stypulkowski

Wakrah and Wukair Drainage Tunnel, WWDT is 13 km long with a 4.5 m ID sewer water tunnel about 50 to 60 m below ground surface. Integral to the project are several adits with provisions for future connections as well as four work shafts, four intermediate access shafts, ancillary hydraulic structures, and an Odor Control Facility. The shaft depths range from 50 to 60 m. The project is constructed in aggressive ground with aggressive ground water. The construction activities require years of pumping and disposal of the ground water during tunneling operations as well as construction of permanent structures in shafts. Grouting of the corrosive rock mass in corrosive groundwater for the WWDT has been described in detail.

Jun 23, 2024

By Jie Zhang, Xi Zhang, Yu Wang, Wei Zhao

The study proposes a novel reagent scheme where adding a small amount of citric acid (CA) significantly improves the depression effect of sodium silicate on calcite and fluorite. The flotation results suggest optimal concentrations for CA and sodium silicate, achieving nearly complete depression of the minerals. Theoretical analysis indicates that CA dissolves calcium ions on the mineral surface, enhancing the adsorption of sodium silicate and preventing collector adsorption.

Mar 27, 2022

By H. L. Holden

The single line grinding circuit at Bond Gold's Colosseum mine consists of variable speed drive semi-autogenous (SAG) milling and secondary grinding with a fixed speed ball mill. There are several advantages and disadvantages of operating SAG mills with variable speed drives. Discussion in this paper will focus on the effects of variable speed SAG milling in relation to mill liner wear, grinding media consumption, and mill operating availability. Operating experiences, corresponding mill data, and pertinent design changes are also presented.

Jan 1, 1991

By Dale R. Andrus

Why is there such an increased thrust toward positive multiple use land management and where will it lead? History and purpose of the mining law of 1872. John Marshall discovered gold at Sutter?s mill near Coloma, California, on January 19, 1848, and utter chaos resulted. The great migration of people to the undeveloped western lands had begun. Prior to this discovery, copper, lead, and iron had been the minerals for which the laws were made. With this discovery of gold on the public domain, it became apparent that congressional legislation was necessary. This became even more apparent as each of the numerous mining districts which were springing up in California, and elsewhere in the west adopted local miners' customs to regulate their activities. Although these early miners acted under mining district rules and in some cases state regulations, they were, in reality, appropriating minerals without sanction of federal law.

Jan 1, 1970

The first session of the Rocky Mountain Coal Mining Institute was called to order by John T. Maulsby, Superintendent of Maintenance and Planning, Columbia-Geneva Steel Division, U. S. Steel Corporation, Dragerton, Utah, representing the past-president. W. K. Dennison, Jr., Superintendent. Koehler line. Kaiser Steel Corporation. Raton, New Mexico, who was unable to attend. Mr. Maulsby welcomed the members and guests, and introduced the President, A. Z. Dimitroff, Mining Electrical Engineer, Health and Safety, District 1-L, U. S. Bureau of Mines. Denver. Colorado. The text of President Dimitroff's address of welcome is as follows: The President's Remarks Guests and Members of the Rocky Mountain Coal Mining Institute: The distinct honor and privilege of officially welcoming you to this, the fifty-seventh regular meeting of the Institute, is indeed a pleasure. Your officers and committees have tried to provide a varied program which I am sure should have something of interest to all of us. The theme of this meeting, "Where Do We Go From here'?", appeared rather fitting for the In¬stitute this year because, as most of you know, until only two weeks ago we thought that this is the last time we will be able to meet at the Colorado Hotel, which has been the favorite spot of most members. Your officers and many of you were literally asking just that question.

Jan 1, 1961

By Rosa Malena Fernandes Lima, Kerollan da Silva Ramos, Joyce de Assis Silva, Geriane Macedo Rocha

This study evaluated the effects of collector type amide-amine compared with those of conventional etheramine acetate (both cationic collectors) on the surface properties of quartz and hematite. An examination of certain properties of the reagents indicated that the new collector amide-amine has CMC (critical micelle concentration) and pKa values (100 mg/L and 8.2, respectively) significantly lower than those of etheramine (800 mg/L and 9.4, respectively). Microflotation tests showed that the recoveries of quartz with amide-amine in all the concentrations tested were higher than those with etheramine. This is attributed to its lower CMC and pKa values. The selectivity window between quartz and hematite flotation using amideamine was higher at pH 10.5 (approximately 80% for 5 mg/L). Therefore, the use of starch is not necessary in siliceous itabirite flotation by amide–amine collector. Zeta potential measurements and infrared spectra reveal that the adsorption of amide-amine collector on quartz surface occurs mainly by electrostatic attraction. Considering the better collectability of amide-amine for quartz flotation and lower adsorption affinity for hematite surface than etheramine, the amide-amine is a promising collector to be used in reversal iron ore flotation.

Jul 30, 2021

By E. Siami-Irdemoosa, S. R. Dindarloo

"Discrete event simulation is a stochastic mathematical modeling tool with applications in queuing systems. Many mining operations, both surface and underground, can be simulated in the context of queuing theory , for example open pit loading and haulage operation, underground level and vertical transportation, and mineral processing circuits. A computer simulation model of the operation is an invaluable tool to study both the system’s dynamics and conducting sensitivity analysis on different effective elements on system performance. In this paper, merits of discrete event simulation in decision making in mining engineering is discussed. Moreover, a stochastic simulation framework for selection and sizing of shovels and dump trucks in surface mining is presented to elaborate one example for applicability of the method in mining operations. INTRODUCTION Mathematical modeling is a valuable tool in design, optimization, and decision making in both surface and underground mining operations. Several researchers have tried to study different aspects of mining operations using a wide range of mathematical techniques such as linear programming[1], analytical hierarchy process [2], non-linear programming[3], genetic algorithms[4-5] ,mixed integer programming [6], machine repair model[7], queuing theory [8], and conventional spreadsheet calculations based on experience and engineering judgments. There are different uncertainties in typical mining operations (e.g. material loading and haulage, drilling, and blasting). For example, in a truck-shovel operation, different governing activities such as loading, haulage, and dumping cycles are stochastic variables. Moreover, analytical modeling of a large truck-shovel operation is very complicated. Thus, application of analytical and/or deterministic techniques cannot guarantee a solution for different problems that are encountered in daily mining operations. Discrete-event system simulation (DES) is a modeling method for such time discrete and probabilistic phenomena [9]. DES has been employed by different researchers in mining engineering through available software and languages such as GPSS, SIMAN- ARENA, and SLAM [10-14]. Most of the studies so far, tried to evaluate some “what-if” scenarios, to understand the possible effects of changing different input variables on overall mine economics. For instance, Baffi and Ataeepur (1996) used Arena to simulate a truck-shovel operation [10]. Also, Sturgul has conducted extensive studies in the application of DES in the mining engineering field [15- 17]. A very good background review of application of this technique in the industry can be found in [15-16]. Previous studies have shown that, different approaches including deterministic, stochastic, and experimental methodologies result in considerable differences in outputs [18]. These techniques lead to different solutions, regardless of the quality of technique/software itself or knowledge of the modeling team. Hence, the first step is to develop a comprehensive simulation framework to obtain nearly the same optimal results for the same input variables, regardless of the employed technique."

Jan 1, 2016

By Martin J. Gavin

During the recent study of lubricating oils carried on in the San Francisco laboratory of the United States Bureau of Mines, it became desirable to distill the oils used in the experimental work at pressures as low as 10 millimeters (mercury column) absolute. In the effort to Overcome difficulties and eliminate sources of error, certain changes were made in the apparatus for vacuum distillation used by the Bureau of Mines for crude petroleum.4 These changes were described in R.I. 2819, issued in July, 1927. Subsequent to the publication of R.I. 2819 several other changes have been made, and the present form of the apparatus for vacuum distillation of lubricating oils is described in this revision of R.I. 2819. These changes were found to give more accurate checks on duplicate distillations. The major part of the credit for the laboratory work which developed the changes in the apparatus and method revised herein is due to Boyd Guthrie, assistant petroleum chemist, and R. V. Higgins, junior chemist, o the San Francisco laboratory, United States Bureau of Mines. DESCRIPTION OF APPARATUS The distilling flask employed is essentially the Hempel flask as used by the United States Bureau of Mines for the analytical distillation of petroleum.5 he complete apparatus is shown in Figure 1. The fractionating column and exposed portion of the flask is wrapped with 4 inch asbestos rope and then surrounded by a cylindrical hood of 1/8 inch pliable asbestos sheet with a narrow air space between the wrapping and the cylindrical hood. This was found necessary to prevent any radiation or convection heat losses from the column, and resulted in obtaining a more even and constant fractionation by eliminating any dephlegmating action caused by temperature changes around the column.

Jan 1, 1930

By Maria Flessas, Justin Ray, Danielle Steinmetz, Brian Zuckerman

"The Ventura County Medical Center Hospital Replacement Wing project consists of the construction of a 2- to 3-story building with a basement encompassing the entire footprint and two corridors connecting the new hospital wing to existing buildings. The site is located in the Ventura Basin where strong ground shaking has been observed during moderate to large earthquakes on nearby faults. The upper 90 feet of the soil consists of loose to medium dense finegrained sands and low plasticity silts that are potentially susceptible to liquefaction, seismic densification, and hydroconsolidation. Ground settlement associated with a large seismic event on a nearby fault is estimated at 20 to 26 inches. To account for the anticipated ground settlement, auger pressure grouted (APG) piles gaining support below the potentially liquefiable soil were selected for the support of the proposed structure. Challenges for pile design included the anticipated earthquake-induced ground settlement, high downdrag loads, low soil lateral capacity during strong ground shaking, and the effect of pile installation on the performance of the existing adjacent buildings and the installed shoring system. The replacement hospital is supported on over 600 APG piles, with lengths varying between 120 and 140 feet. Axial pile capacities were verified with an extensive indicator pile installation program and dynamic pile load testing.INTRODUCTIONThe Hospital Replacement Wing (HRW) project is at the Ventura County Medical Center (VCMC) in Ventura County, Southern California (Figure 1). The VCMC consists of three interconnected hospital buildings (Buildings 303, 304, and Fainer Building), the Medical Laboratory/Cafeteria Building, two mental health buildings, a medical office building, an emergency generator building, and surface parking lots. The HRW is near the center of the campus, adjacent to several existing buildings.The HRW is a 2- to 3-story structure, with a 15- to 20-foot-deep basement beneath the entire 95,000-square-foot building footprint. The HRW project includes a Loading Dock, a four-level corridor to the Fainer Building (Fainer connector), and a two-level corridor to the Medical Laboratory/Cafeteria Building (Café connector). The corridors are structurally separated from the existing buildings. Typical dead plus live load column loads for the HRW range from about 635 kips to 935 kips and total loads range from about 860 kips to 1,295 kips."

Jan 1, 2016

By Sharif Jahanshahi

Calcium ferrite slags are often associated with Professor Yazawa due to his pioneering work on the thermodynamics of this type of melts. Over the past years CSIRO has invested some effort in studying physico-chemical properties of such melts to fill in some gaps in our knowledge and explore opportunities for application of the understanding developed. These investigations cover thermodynamics, transport properties of calcium ferrite based slags, as well as the kinetics of reactions of such slags with refractories. The present paper provides an overview of some of these studies and highlights some of the interesting behavior of such melts. The oxidation state of copper and arsenic in calcium ferrite based slags are predominantly Cu+ and As3+, respectively, at oxygen potentials below 10.1 atm. The concentration ofCu2+ in such slags becomes significant at oxygen potentials of greater than 10'1 atm at 1300 ?C. The activities of CuOo.s and AsOl.S in calcium ferrite slags show strong deviations from the Raoultian Law, while that of CoO is very close to ideal behaviour with respect to pure solid CoO. Addition of Si02 to calcium ferrite slags can have significant effects on the activities of FeO and Fe2O3 and hence the stability of magnetite phase. Transfer of oxygen in calcium ferrite slags is fast with diffusivity of 2xlO?3 cm2/s at 1350 °C and activation energy of 16 kcal/mol Presence of solid phases, such as magnetite, has pronounced effect on the viscosity of calcium ferrite slags. The observed dependence on solid loading and shear rate indicates deviation from Newtonian behaviour. The interfacial tension between copper mattes and calcium ferrite slags is strongly dependent on the matte grade, with the determined values being much lower than the corresponding ones for interfacial tension between similar mattes and iron silicate slags. MgO, Cr2O3 and MgCr2O4 have low solubility in calcium ferrite slags and their solubility increases with increasing copper oxide content of the slag at 1300 °c. The oxidation state of the slag has strong effects on phase transformation, dissolution rate and disintegration of refractories in calcium ferrite slags. Other key factors with major impact on slag-refractory interactions include viscosity and surface tension of slags as well as the contact angle between slag and refractory material.

Jan 1, 2003

By Juan M. Pestana, Jeremy M. Gasser, Cuneyt Gokmen, Paul J. Sabatini, William Tanner, Daniel J. Woeste

An access pathway and working platform were designed and constructed for equipment access for a Deep Soil Mixing (DSM) pilot study over a coal combustion residual (CCR) surface impoundment (SI). The DSM pilot study was conducted to evaluate slurry mix designs and construction techniques for installing DSM columns up to 95 feet deep. Two-dimensional (2-D) limit equilibrium and 2-D finite element analyses were used to evaluate multiple failure mechanisms including: (i) bearing capacity, (ii) punching shear of mixed ground and underlying CCR, (iii) effect of fluidized DSM columns on working platform stability, and (iv) liquefaction. The analysis results were used to design ground improvement required to increase bearing capacity and stability of the CCR under the proposed equipment access route. A long-reach excavator was used to perform shallow bucket mixing and walk onto the CCR SI atop previously mixed cells following a minimum cure time and acceptance of quality control test results. Prior to mobilizing the DSM rig, a static load test was conducted to evaluate performance of the working platform. Both the access pathway and working platform demonstrated acceptable performance under the design loads during the DSM pilot study. This case study emphasizes the economic and safety benefits that can be realized by appropriately designing critical temporary work items such as access pathways and working platforms in difficult ground conditions. INTRODUCTION A Deep Soil Mixing (DSM) pilot study was conducted at a coal combustion residual (CCR) surface impoundment (SI) to evaluate slurry mix designs and construction techniques for closure design of the SI (Site). Sluicing of CCR at the facility ceased and closure will be initiated based on requirements in the final United States Environmental Protection Agency (USEPA) Rule for Disposal of Coal Combustion Residuals from Electric Utilities, 40 CFR 257, effective October 19, 2015. The proposed closure approach involves constructing a DSM containment structure (DSM Wall) to separate the SI into two areas: (i) a closure by removal area; and (ii) a consolidate and cap-in-place area. The proposed DSM Wall would retain the CCR within the consolidated closure footprint and provide a barrier between the two areas of the SI. The predominant CCR in the SI where the pilot study was conducted were fly ash and bottom ash. CCR materials in surface impoundments are generally soft and saturated as a result of being sluiced into place and can present stability and safety challenges when performing earthwork activities.

Jan 1, 2019

By S P. Young, K R. Monro

Reducing metal prices have forced mining operations to become more efficient and innovate in order to do more with the existing base. Much of this effort has focused on improving the efficiency of load and haul operations. The key to this is to understand and quantify where delays and missed opportunities exist. Metrics such as utilisation of availability, efficiency utilisation and asset availability are helpful indicators of performance; however, uptime-based time usage models and performance analysis tools using productive operating time models help to identify additional improvement opportunities.Phu Kham is a copper-gold mine operated in the Lao People’s Democratic Republic (Laos) since 2008 by PanAust Limited. The mine is a single large open pit of 450 m depth, running a fleet of 51 100 t class rigid dump trucks and 300 t and 200 t shovels controlled with the aid of a fleet management system in order to achieve ex-pit material movements of 56 Mt/a.Commencing in late 2014, a range of initiatives were implemented in order to improve the efficiency of the mine haulage fleet. These include hot seating of all operator changeouts via changeout ramps, split shifting of crews to minimise queuing delays, maximising blast volumes and minimising blast event days to reduce blast exclusion delay events including opportune refuelling of equipment during blasting events, inspections of trucks during refuelling events, implementation of a dedicated haul road services team to help reduce wet weather related delays and infrastructure development for haul path efficiency improvements.These and other initiatives have allowed the mine haulage fleet utilisation of availability (UofA) to be sustainably increased from 85 per cent to 97 per cent (see Figure 1), efficiency utilisation to increase from 85 per cent to 90 per cent, and productive operating time (POT) to increase from 73 per cent to 84 per cent. The corresponding increases in efficiency of the haulage fleet has allowed an equivalent reduction of eight haul trucks from the fleet to meet continuing life-of-mine production requirements.CITATION:Monro, K R and Young, S P, 2016. Truck haulage improvements at the Phu Kham mine – the journey to 97 per cent utilisation of availability, in Proceedings International Mine Management Conference, pp 339-346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By G. E. Keller

In connection with the work of Committee D5, Coal and Coke, of the American Society for Testing and Materials in developing new standards and improving old standards, series of tests were made to check the variance of sample preparation and analysis of American coals. Table I in the "Tentative Method of Preparing Coal Samples for Analysis - 02013-62T" is rather complicated, and the tests were designed to develop data for the simplification of this table. An allowance of 20% of the total variance of sampling and analysis for the sample preparation and analysis steps was used. Also, instead of coals being grouped into ash ranges, they were grouped as washed and raw (unwashed) coals. As a result of these tests, a simplified Table I for Tentative Standard 02013 has been proposed. A standard test for laboratories to check their variance of sample preparation and analysis has been developed. Committee D5 on Coal and Coke of the American Society for Testing and Materials has been making a study of all standards applying to coal for the purpose of improving and bringing them up to date and for breaking some of the existing standards covering a number of tests into single standards. As an illustration, sample preparation is now partly covered in ASTM Designation D492-48, Sampling Coals Classified According to Ash Content, and partly in ASTM Designation D271-58, Laboratory Sampling and Analysis of Coal and Coke. The latter contains, in addition to parts of sample preparation, methods for determining Moisture, Ash, Volatile Matter, etc. Although revision of sampling methods and sample preparation methods are now assigned separately, it is possible that they may end up as one standard. One of the first new Tentative Standards developed as the result of these studies was ASTM Designation D2013, Tentative Method of Preparing Coal Samples for Analysis. Although this method is quite an im- provement over that in the old standards and gives very specific instructions, Table I (attached) is quite complicated and rather hard to understand. In order to take advantage of reduced quantities or weights, it is necessary to know the ash content within rather narrow limits before sample preparation and no distinction is made as to whether the coal is cleaned or uncleaned. No limits of accuracy are assigned to the sample preparation and analysis. The total over-all accuracy of sampling, preparation and ash determination as given in D492-48 has been specified for commercial sampling procedure as follows: "This procedure is intended for an accuracy such that if a large number of samples were taken from a single lot of coal, the test results in 95 out of 100 cases would fall within ? 10 per cent of the average ash content of the sample." Although Appendix 11, Method for Determining the Over-All Variance of Reduction and Analysis in the Tentative Methods for Mechanical Sampling of Coal, ASTM Designation D2234-63T, does give a method for determing the over-all accuracy of preparation and analysis expressed as variance and also the F test, it does not permit the determination of the variance at the various stages of reduction or of the ash determination. It was decided in 1961 to ask a number of laboratories to run a series of tests for the purpose of determining the variance at various stages of reduction and analysis with the view of simplifying Table I of the Tentative Standard D2013-62-T. This paper is a record of this series of tests with recommendations which resulted from the tests. At the same time and preceding these tests the International Organization for Standardization under Committee TC/27 WG 7 was studying the same problem. Tomlinson1 of England and Dr. paul2 of West Germany had made studies giving quite a bit of information. Also Schwerd and coryel13 published some information which was the main basis for the Mechanical Division provision in ASTM Tentative Standard D2013-62T, Table I. In checking with the various laboratories which offered to cooperate in these tests, none was found which used mechanical division through the entire preparation procedure. It was then decided to use riffles at all stages with the thought that if riffles gave satisfactory variances, approved mechanical

Jan 1, 1965

By Elio Flórez

El presente trabajo refiere la utilización práctica de las escorias metalúrgicas -en tanto material de aislamiento térmico-. La lana de escoria es conocida como "lana mineral", cuya industria se inició en 1897. La manufactura suelta no es el producto final, sino la materia prima, que será tratada en un proceso seco para obtener las diferentes formas de productos y adaptarlas a distintos usos. La lana de escoria puede ser usada como aislante térmico, en absorción de sonido y también como medio de filtración y material de relleno. En el primer caso, se utiliza en casas y edificios, hornos, duetos de aire acondicionado, salas frigoríficas para alimentos, tanques de agua caliente, calderos, intercambiadores de calor, tuberías, etc. Mientras que en el segundo caso se utiliza para extraer polvo, agua de aire o gases. Asimismo, los productos de lana de escoria son la granulada, acolchada en mantas, en bloque, en planchas comprimidas, en formas moldeadas, las cuales tienen una densidad instalada desde 2-lb/pies3 en las formas más-79- livianas, hasta 16 lb/pies 3 en las formas semi-rígidas.

Aug 20, 1963

By Magnus Ericsson

The unexpectedly quick recovery in world crude steel production in the second half of 2009 was due almost entirely to increased production in China that began in late 2008. Previous peaks in monthly production in China were matched by April 2009. The rest of the world had still not reached pre-crisis production rates by May 2010. Chinese production drives growth, but there has been some growth in most other larger crude steel producing countries as well, compared to production in 2009. If the production rate of the first four months of 2010 continues, the total output of crude steel in 2010 will be somewhere around 1,410 Mt (1.5 billion st), the same as in the record year of 2007.

Jan 1, 2010

By Hatch, A. Reple, W Valery

The mining industry is facing declining feed grades which require the mining and processing of larger volumes of material per tonne of product. Pre-concentration aims to remove barren material at as coarse a particle size and as early in the process as possible to reduce processing costs, energy consumption, water losses, and greenhouse gas emissions while increasing production and profitability. This may be achieved using bulk ore sorting—the separation of barren gangue from a fully loaded conveyor belt based on the grade as measured or inferred from a sensor. This paper evaluates the technical and economic viability of bulk ore sorting for the PanAust Phu Kham copper deposit in Lao PDR. Bulk ore sorting technology is described briefly along with discussion of appropriate sensor and diversion systems for the Phu Kham operation. To evaluate the economic implications, the actual mined material and costs from 2014 were used as the base-case. Sampling data was not available; therefore, the ore grade variability that would feed a bulk ore sorter was estimated using geo-statistical tools based on mine grade control data. The sorter performance when treating this material was simulated considering the accuracy of the sensor measurement and errors associated with material diversion. The impact on inferred cash flow was estimated for several different scenarios considering the additional costs for sorter operation and reject handling. The evaluation demonstrated that bulk ore sorting at Phu Kham has the potential to increase the amount of metal in product and/or reduce processing plant throughput (and costs) to improve the annual inferred cash flow for the conditions investigated. The sorter is the gatekeeper – only material above the cut-off grade (value-adding) reports to the processing plant; no waste dilutes the feed. Likewise, above cutoff grade material is not lost to waste; preventing lost revenue.

Jan 1, 2016