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By P. Altounyan

Techniques used to safely control the roof in UK coal mines for some 10 years have been applied to a South African coal mine. This new approach known in the UK as advanced rockbolting technology, is based on applying four fundamental principles: ?Understanding the roof failure mechanisms ?Using an effective roof support system ?Designing this support using measurement ?Monitoring the performance of the system. The paper summarizes the approach in detail and describes how it is being applied by Anglo Coal, giving results obtained to date. Investigations at a number of South African coal mines, including stress measurements at two Anglo Coal mines, have confirmed that the mode of roof failure (lateral shearing due to horizontal stress) is the same as in other coalfields worldwide, and aspects of current world best practice, including the use of advanced technology rockbolting, are therefore relevant in South Africa. The stress measurements indicated a high level of stress field anisotropy and further investigation of stress conditions in South African coal mines is recommended. The most effective bolting system to resist shear failure is one with high bond strength and stiffness. Short encapsulation pull testing of existing South African systems confirmed that they have low bond strength and stiffness. An improved rockbolt system with the required performance, and features allowing rapid installation and installation quality and performance audit, has been developed and is currently under full-scale trial. Design by measurement and routine monitoring procedures including the use of a rotary telltale device are also under trial. It is anticipated that South African coal mines will be able to obtain significant safety and productivity benefits from the application of this technology.

Jan 1, 2001

By Associates

The headwaters of Skippers Creek and the Shotover River are reputed to be among the richest alluvial gold catchments in the world. This alluvial gold has no doubt been derived from reef systems similar to, and associated with, the Bullendale lodes. Physiographically the prospect covers steep ridges and deeply incised gullies between the Richardson Mountains in the west and the Harris Mountains in the east. Vegetation is mainly tussock with bush either side of Murdochs Creek. Access to the area is by metalled road to Skippers and then by 4WD track to Bullendale. Alternatively the prospect area can be reached by helicopter from Queenstown in around ten minutes.

Jan 1, 1992

By T. C. Pool

Physical and chemical conditions permitting, in-situ leaching (ISL) of uranium offers a variety of advantages over conventional production methods including less surface disturbance and less solid waste. Commercial production of uranium by in-situ leaching techniques was initiated in 1963 in the Shirley Basin of Wyoming by Utah Construction. On a world-wide basis, ISL uranium production amounted to about 13.2 million pounds U3O8 in1999, approximately 16% of world output. Both acid and alkaline systems are used, the selection of which is primarily dependent upon groundwater quality and related reclamation requirements. ISL offers low capital costs per unit of annual capacity and is particularly flexible in adapting to changing market conditions.

Jan 1, 2000

By Munro P. D

Eh-pH measurements were taken on an industrial zinc reverse flotation process at Brunswick Mining and Smelting Corporation Limited. Laboratory zinc reverse flotation testwork on samples of the feed to the industrial process produced Eh-pH data which were similar to the data from the industrial process.Later, the Eh-pH data from the industrial process were compared with data from a pilot plant scale zinc reverse flotation process at Mount Isa Mines Limited. After comparison with the data from Brunswick Mining and Smelting Corporation, deficiencies in the pilot plant Eh-pH data could be recognised and corrective actions were taken for the pilot plant. A robust pilot plant zinc reverse flotation process was obtained with consistent performance at the expected level.The implications of these findings for a range of processes are also discussed.

Jan 1, 1988

By Ali Mortazavi

In underground mining applications, successful blasting results in less damage, which may lower support costs, lower dilution and produce a uniform fragmentation. The explosive detonation process creates a pressure front that propagates a stress wave into the surrounding rock mass at a high velocity. The stress wave can induce varying degrees of damage, depending on rock strength and physical properties, to the excavated area. This paper presents a summary of a research project that was conducted to investigate the propagation of explosive-induced stress waves in hard rock media and the mechanism of rock damage and fracturing due to shock wave propagation. The primary objective of this work was to numerically simulate the experimental study of blast-induced rock fracturing conducted within Inco Limited, Mines Research department. ITASCA?s discontinuum code UDEC (Universal Distinct Element Code), was used to simulate the results of the controlled blasting experiments. In brief, the focal point of the paper can be summarized as follows: ? Investigate the size of the stress-wave-induced fractured zone around the blasthole, ? Examine the extent and direction of the radial fractures that form outside the blasthole, and ? Explore the mechanisms that cause rock breakage.

May 1, 2002

By B Vernon, M Whiteley, T Robinson

The Western Australian gold industry has approximately 100 operating plahts, mainly CIP/CIL. The nature of the State's rapidly expanding gold industry gave rise to concerns over management of the  cyanide hazard, in that most plants are remote from major population centres, have a workforce with a high tum over and use highly saline process water. Approximately 4500 workers in the industry have the potential to be exposed to cyanide in the course of their normal work.   This paper outlines the risk management strategy developed by Government and industry to monitor atmospheric HCN gas in the work environment and the role of continuing education and training along with regular site inspections by Department of Mines Inspectors.

Jan 1, 1990

By Robert S. Becker

The results of a laboratory investigation of coal cutting mechanics and noise is presented. These experiments were performed using a linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts is ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to Formulate analytical models of the coal cutting forces and noise. The analytical model For coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator's position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as Provide benefits to other important areas of underground health and safety.

Jan 1, 1980

By Mary Ellen Bruce Large, Antonio Marinucci, Silas C. Nichols

Tip post-grouting of bored pile (drilled shaft) foundations refers to a method where cementitious grout is injected beneath the tip of a shaft to improve the overall performance of the constructed foundation. This technique, when performed satisfactorily and in the appropriate ground conditions, enhances axial load-displacement performance by improving the mobilization of pile’s resistance. Potential benefits associated with tip post-grouting include reduced settlement under loading, better alignment of load transfer curves, and improved ground beneath the base of the bored pile. However, to be able to realize the benefits attributed to this method, the design, construction, of both the bored pile and the post-grouting system must meet a minimum level for quality assurance. The various factors affecting the successful installation and performance of a bored pile (e.g., workmanship, base cleanliness, borehole integrity, and concrete placement) have been discussed by numerous practitioners and researchers in the available technical literature. For a conventional (i.e., ungrouted) bored pile, acceptance is based on a combination of visual inspection, material testing, and the results of integrity and/or performance testing of the constructed pile. A properly executed tip post-grouting program can be a relatively comprehensive and complex process, which is typically evaluated throughout the construction process based on the results of prior projects and/or on test pile(s) at the particular site. For tip post- grouting programs, verification procedures and acceptance criteria should be established during and incorporated into the design process to ensure design intent and objectives are achieved. Project specifications should be produced to ensure performance requirements are achieved. This paper will present and discuss factors affecting the successful execution of tip post-grouting, including grouting criteria, instrumentation, reliability and uncertainty with the method and outcome, and verification and acceptance. INTRODUCTION Constructing bored piles (drilled shafts) is increasingly more challenging given the lack of ideal site locations, tight project site confines, difficult or restricted access, greater demands on drilling equipment, and close proximity to adjacent structures. To evaluate the feasibility of bored piles as an appropriate foundation system, a myriad of factors is evaluated during design, including site conditions and constraints, budgeting and scheduling, reliability and risk exposure, presence of and depth to adequate load bearing soils/rock, and the magnitude of the imposed loading. Moreover, updated design codes increased load demand per element, and improved material strengths have led to more complex foundation designs, larger foundation elements, and significant increases in load magnitude. Monopile (monoshaft) foundations have been utilized where one large bored pile is used in lieu of a group of piles connected via a pile cap. In addition, to accommodate the design criteria, site conditions, and imposed loading, the geometry of the bored piles being designed and installed have been as large as 13 feet (4 m) or greater in diameter and to depths in excess of 260 feet (80 m).

Jan 1, 2018

By Robert S. Shank

Introduction The Pinto Valley open-pit copper mine is located in southern Arizona, 11 km (7 miles) west of Miami. Production at Pinto Valley began in 1974. About 350 Mt (386 million st) of ore and waste was removed by the end of June 1982. At that time, the mine was using more than 90 major equipment items with a total mobile fleet numbering 320. Some of the major equipment consisted of four Marion M4 rotary drills; six P&H 15, 11.5- and 19.1-m3 (15- and 25-cu yd) shovels; and 24,136- and 154-t (150¬and 170-st) Wabco haulage trucks. This equipment was used to move more than 139 kt/d (154,000 stpd) of ore and waste. The mill was processing more than 50 kt/d (55,000 stpd) of mine ore. Shutdown A two-week vacation shutdown began in July 1982. Maintenance jobs were scheduled, and most employees left for the vacation. During the vacation period, copper prices fell below $1.32/kg ($0.60 per lb). Inventories remained at alarmingly high levels. At this point the mine was losing more money operating than it would by being shut down. The vacation shutdown was first extended to five weeks. But, after further evaluation, the mine was shut down indefinitely. In Dec. 1982, Cities Services Co., owner of Miami Operations (which included the Pinto Valley mine and mill), was acquired by the Occidental Petroleum Corp. On March 1, 1983, Occidental sold the operations to Newmont Mining Corp., and Newmont created Pinto Valley Copper Corp., as a wholly owned subsidiary. Copper continued to be produced by the Pinto Valley solvent extraction-electrowinning (SX- EW) plant because of its low cost per pound of production. To ensure proper equipment care during the shutdown, maintenance management was given three goals; • maintain the SX-EW plant; • maintain the environmental and pollution control systems such as domestic water pumps and mine dewatering; and

Jan 4, 1985

This international symposium was convened to assess the current state of knowledge concerning the health hazards that might be associated with the ingestion and inhalation of fibrous particles produced from the processing of taconite ore. Concern about fibrous particles in taconite arose from their similarities to amphibole asbestos minerals that are known to be human carcinogens. The mineralogical characteristics of asbestos fibers are reviewed and compared with the fibrous particles known to be present in taconite ore from the eastern end of the Iron Range. The epidemiological and experimental animal studies for asbestos-related disease (including gastrointestinal cancer from asbestos in dinking water)were critically evaluated andcompared to those of the fibrous minerals in the taconite. The focus was on the amphiboles in the cummingtonite?grunerite and tremolite?ferroactinolite series and other fibrous particles in both the Iron Range and the Duluth Complex. This included examination of the reported occurrence of any asbestiform ferroactinolite, crocidolite asbestos, chrysotile asbestos, etc. In addition, an effort was made to provide a scientific framework to address fibrous minerals, which may be associated with nonferrous mineral deposits in the Duluth Complex. State-of-the-art risk assessment models for asbestos were presented. Risk assessment scenarios were developed for taconite-derived fibers at environmental exposure levels related to the operation of the Silver Bay taconite processing facility. These calculated risks were found to be trivial even after it was assumed that all mineral fibers were as carcinogenic as amphibole asbestos.

Jan 1, 2008

By Steve Custer, Tim Kahl, Sue Parker

"The primary objective of the Barrick Goldstrike expert system is to achieve the desired liberation size for the autoclave circuit while maximizing throughput. In addition, when downstream limitations (autoclave circuit or others) restrict the milling circuit tonnage the expert system further improves grinding product size. Since its implementation, the expert system has provided expected throughput improvements while improving or maintaining circuit performance.Barrick Goldstrike and MinnovEX Technologies Inc. teamed up to install an expert system to control Line I and I1 of the autoclave grinding circuits. The dissimilar equipments of the two grinding circuits coupled to different production objectives, skepticism among operators, and the variability of the ore types processed in each line challenged the implementation.To ensure implementation success, Barrick Goldstrike dedicated four administrators full time to the project. The system administrators included two metallurgists, a process control engineer and a mill trainer. As usual, the control room operators were the experts who provided the operational logic for the foundation of the control system. The administrators and all eleven of the control room operators signed off on acceptance of the system. Current online utilization is 95%.INTRODUCTIONThe grinding circuit for Barrick Goldstrike’s autoclave process consists of two SAG Mill Ball Mill lines. Line 1 grinding circuit is comprised of a 22 by 8 foot, 2500 horsepower Allis Chalmers (AC) variable speed SAG mill, followed by a 12.5 by 14 foot, 1250 horsepower AC ball mill, and a 13.5 by 18 foot, 1800 horsepower Dominion ball mill in parallel. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1352 Nordberg Omnicone crusher (4.5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The ball mill circuit is closed with 6 Krebs super D20 cyclones. Line 2 grinding circuit is comprised of a 24 by 12 foot 4000 horsepower Fuller variable speed SAG mill followed by a 16.5 by 30.5 foot 5000 horsepower Fuller ball mill. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1560 Nordberg Omnicone crusher (5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The line 2 ball mill circuit is closed with 12 Krebs super D20 cyclones. The underground Meikle ore is typically fed through Line 1. Achieving the desired product size is critical for successful processing of Meikle ore. Open pit Betze ore is fed to Line 1 when Meikle ore is unavailable. Line 2 processes Betze ore exclusively. Throughput is maximized when processing Betze ore as the product size is less critical. The products of these two circuits are combined as feed to the autoclave circuit. The ore types and the autoclave circuit demands determine the required grinding circuit product size and maximum combined mill feed tonnage."

Jan 1, 2001

By J. P. Ducarme

Numerous fatal/nonfatal accidents involving underground workers struck by powered machinery occur yearly, with continuous miners and roof bolters involved in the majority of these accidents. In an attempt to reduce these accidents, researchers at the the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Research Laboratory conducted studies of operator interactions with the motions of continuous mining machines and roof bolter boom arms. These operators generally perform their tasks in close proximity to the equipment in confined workspaces, often employing awkward postures. Since experiments with human subjects using the actual equipment were not feasible due to safety concerns, researchers opted to conduct controlled experiments in laboratory settings. Utilizing motion capture technologies and computer simulations, the studies collected data on equipment and operator movement in a range of seam heights and working postures. This article details the results of these studies to examine operating speeds based on usage and seam height.

Jan 3, 2010

By P. Zhang

The use of phosphate depressants in the cationic flotation of silica from francolite in the Florida phosphate industry is rarely practiced. The occasional use of gelatinized starch derivatives and pH adjustments to assure a slightly alkaline flotation feed slurry pH have been used in some processing plants to improve selectivity. This paper presents a preliminary laboratory comparison of several potential phosphate depressants for use with the flotation of siliceous phosphates. It was found that starch is ideal for floating fine (-35 mesh) silica from phosphate, while sodium tripolyphosphate may be the best for coarser (+35 mesh) feeds.

Jan 1, 2009

By M. Kwasniewski, M. Takahashi

Prismatic samples of a medium-grained sandstone from Slask Colliery (Upper Silesian Coal Basin, Poland) were tested under uniaxial compression, conventional triaxial compression and true triaxial compression conditions. The conventional triaxial compression tests were carried out at confining pressure (p) equal to 12.5, 25.0 and 37.5 MPa. In the true triaxial compression tests the minimum principal stress (s3) was equal to 25.0 MPa and the intermediate principal stress (s2) was 1.5, 2 and 2.5 times higher than s3. Results of the studies show that confining pressure strongly inhibited dilatant behavior of rock samples tested under conventional triaxial compression conditions; the increasing confinement resulted in the growing compaction of the rock material. The effect of dilatancy was also highly suppressed by the intermediate principal stress. While important dilatant, negative volumetric strain corresponded to the peak differential stress at low intermediate principal stress conditions, at high intermediate stresses the rock material was damaged to much lesser extent. As a result, faulting of rock samples in the post-peak region was much more violent and was accompanied by a strong acoustic effect. Les échantillons parallélépipédiques du grès à grains moyens de la mine ‘Slask’ (Bassin Houiller de Haute Silésie, Pologne) ont subi les essais de compression monoaxiale (compression simple), de compression triaxiale conventionnelle (compression triaxale de révolution) et de compression triaxiale vraie. Les essais de la compression triaxiale conventionnelle ont été effectués à la pression de confinement de 12,5, 25,0 et 37,5 MPa. Dans les essais de compression triaxiale vraie la contrainte principale minimale (s3) était de 25,0 MPa et la contrainte principale intermédiaire (s2) était 1,5, 2 et 2,5 fois supérieure de s3. Il résulte des essais que la pression de confinement inhibe fortement le processus de dilatance dans les échantillons testés dans les conditions de compression triaxiale conventionnelle; l’augmentation de la pression provoquait l’augmentation du compactage du matériau rocheux. Le phénomène de dilatance était également limité de façon significative par la contrainte principale intermédiaire. Alors que l’importante déformation volumique négative correspondait à la contrainte différentielle ultime avec les faibles contraintes principales intermédiaires, dans les conditions de fortes contraintes intermédiaires, le matériau rocheux subissait l'endommagement de façon beaucoup moins importante. En résultat, la rupture des échantillons rocheux au stade post-maximum était beaucoup plus violente et accompagnée d’un fort effet acoustique. Prismatische Probekörper des mittelkörnigen Sandsteines aus dem Bergwerk ‘Slask’ (das Oberschlesische Kohlengebiet, Polen) wurden unter der einaxialen Druckbeanspruchung, konventionellen dreiaxialen Druckbeanspruchung und der echten dreiaxialen Druckbeanspruchung geprüft. Konventionelle dreiaxiale Druckversuche wurden bei dem Manteldruck von 12,5 25,0 und 37,5 MPa durchgeführt. Bei den echten dreiaxialen Druckversuchen betrug die kleinste Hauptspannung (s3) 25,0 MPa und mittlere Hauptspannung (s2) war 1,5-, 2- und 2,5-mal höher als s3. Aus den durchgeführten Versuchen ergibt sich, dass der Manteldruck die Dilatanzentwicklung bei den Probekörpern unter der konventionellen dreiaxialen Druckbeanspruchung stark bremst; die Erhöhung des Druckes rief die ansteigende Kompaktion des Gesteinsmaterials hervor. Die Dilatanz wurde auch durch die mittlere Hauptspannung beschränkt. Während die wesentlichen volumetrischen, dilatanten Verformungen der Grenzdifferenzspannung bei den niedrigen mittleren Hauptspannungen entsprachen, bei den hohen mittleren Hauptspannungen wurde das Gesteinsmaterial viel weniger beschädigt. Im Ergebnis war der Scherbruch der Gesteinsproben im Post-Peak-Bereich viel heftiger und mit kräftigen akustischen Effekten verbunden.

Jan 1, 2003

By T. R. Wildeman

"At the Big Five wetland, which was built to treat drainage from a metal mine, encouraging results have attributed to sulfate reduction. Cu and Zn were reduced to below detection limits of 0.50 mg/L, Fe was reduced by at least 90% to below 3 mg/L, and the pH was raised from below 3 to above 6. The study showed that treatment was primarily through microbial processes within the substrate and that plants were not needed to insure success.Constructed wetlands can be taken through design and proofing stages, and into operations scale in a meaningful time frame for on-line acid drainage remediation. In staged design, laboratory experiments are initiated to determine reasonable substrate materials for remediation of a particular drainage. When a reasonable substrate is found, bench scale experiments are initiated as the next stage in the design. In these studies, removal efficiency, permeability, and flow are analyzed to identify candidate substrate which will support sulfate reduction and be hydraulically reasonable. Using this design method at one site, an acid drainage of pH 2.5 was raised to a pH of above 7. Total heavy metal concentrations in this drainage exceeded 900 mg/L. In the pilot constructed wetland Cu, Zn, and Fe were reduced by 99%.Determining how well these anaerobic cells operate in the winter is done at the pilot plant site in Idaho Springs, CO. It's been found that over the last four winters, those cells that emphasize anaerobic removal within the substrate have operated continuously and effectively the year round. Winter operation is aided by the fact that the water temperature of the acid drainage is always between 14 and 16° C, and the cell can be readily insulated from the cold. Activity of the sulfate reducing bacteria may decrease during the winter. However, it appears that organic complexation of metals helps to maintain low concentrations of metals in the effluent."

Jan 1, 1992

By Eduardo Nunez, Asim Tuzun, Dan Graffi, Glenn MacPherson

"In preparation for the milling of a new nickel and copper mine ore, Nickel Rim South, Xstrata’s Strathcona Mill is undertaking numerous process improvement projects. Within the grinding circuit, several projects are under development and an automated grinding control strategy, consistent with the operating objectives, was identified as a key requirement. The grinding strategy is to maximize the throughput (quantitative objective) while maintaining the cyclone overflow within specifications (qualitative objective).This paper describes the implementation of a robust grinding control strategy using the existing control system. The implemented controls maintain the cyclone overflow density at the desired target, while continually optimising the rod mill feed rate to allow maximum throughput. This approach has the added benefit of improving the stability of the rougher flotation circuit down stream of the grinding and improving energy efficiency of the rod and primary ball mills. This paper discusses the comparison of the before and after the implementation of results.INTRODUCTIONThe grinding process is a size reduction operation used in the mining industry to liberate the valuable minerals from the gangue. Grinding is one of the most important and expensive processes in a concentrator (Xi-song, 2007; Pomerleau 2000; Najim 1995), often accounting for around half of the total operating costs in base metal concentrators (Wills, 1990), which has led to a focus on development and implementation of control and optimisation strategies. The grinding process prepares the ore for the subsequent concentration step, which for sulphide base metal operations, is predominantly flotation. The performance of the concentration (flotation) is very much determined by the feed characteristics of the slurry coming from grinding. The valuable minerals recovery process in flotation is very much influenced by the grinding process and the liberation of the desired minerals from the gangue minerals (McIvor, 1991).The true objective of grinding is to obtain a proper liberation of the minerals as defined by a particle size distribution referenced typically by d80 (80% passing size of product). Besides achieving the desired mineral d80 size, it is clearly desirable to produce as narrow a size distribution as possible to squeeze the maximum amount of the mineral value into the highest recovery region (McIvor, 1991). This is an important criterion for the mill in economically optimizing the grade and recovery for the concentrate product. It is important not to over or under grind, while keeping the specific comminution energy as low as possible (Nunez, 2005) to achieve the target liberation. In other words, maintain an optimal throughput depending on the ore conditions to the capacity of the grinding mills, while providing the flotation process with a constant and narrow size distribution, at a cut size selected to meet the metallurgical requirements (Bascur, 1991)."

Jan 1, 2009

By D. Kwietnewski

With all of the unknowns associated with tunnel construction, how does a contractor choose a roadheader? This paper presents a review of several models of roadheaders being used in today?s tunnel projects. The features of different models of roadheaders are presented and compared. Roadheader size and cutter power generally determine which roadheader is best for a particular job. We will also present a model for matching features of the roadheader to the anticipated ground conditions such that the most efficient machine is selected for the project.

Jan 1, 2011

By Brian Langdon

The DRIVEN GROUT PILE was developed in 1989 by DeWitt Construction, Incorporated. This piling essentially consists of a cost-in-place concrete piling that reacts on a steel boot that is driven to bearing. This report will describe the driven grout pile, its background and its installation. The advantages and disadvantages of this system are also discussed. Finally, the results of actual field installations are presented and discussed. BACKGROUND The DRIVEN GROUT PILE was developed out of a need for a low-cost high capacity piling (100 ton) that could be installed with ordinary pile driving equipment. This search was motivated by attempting to incorporate the material economy of an auger-cast piling with the "empirical load test" of a driven pile. Typically, the least cost material for piling in the 100 ton range is concrete (grout). A grout shaft with minimal reinforcement can withstand a compressive load of 100 tons for a material cost in the range of $6.00 to $8.00 per lineal foot. A pipe piling with a capacity of 100 tons has a unit material cost ranging to $13.00 per lineal foot. The marriage of these two advantages resulted in the DRIVEN GROUT PILE. A pile that utilizes the economy of a reinforced grout shaft and has the loading confidence of a driven pile.

Jan 1, 1990

By M J. Kongas, K M. Saloheimo

This paper presents the art of on-stream particle size and elemental analysis used at iron ore concentrators, followed by the results and experiences from several sites.Online particle size analysis is rather common at medium- to large-sized concentrators. Online X-ray fluorescence (XRF) elemental analysis, however, is only used in some iron ore concentrators, while it is a routine practice in base metal concentrator plants. Online XRF analysis is applicable for process monitoring and control down to four to five per cent silica by measuring Fe assays accurately. With lower silica content, direct measurement of silica and other light elements is required. Some light element analysers that are based on the prompt gamma neutron activation analysis (PGNAA) method have been developed, but they have not performed up to expectations with slurry analysis. Other methods have been tried though these have not been used beyond prototype installations. Operating online light element slurry analyser installations are not common in iron ore applications.There is an economic incentive to mine lower and variable grade iron ore resources, which require concentration and removal of several impurities to produce high-quality concentrates for pellet production. Monitoring such operations by on-stream analysis has significant economic benefits, and there is a need to develop a dependable slurry online analyser for Si, Al, Mg and other light elements. The latest developments in slurry on-stream light element analysis are described.CITATION:Kongas, M J and Saloheimo, K M, 2013. Online slurry analysis for process control and monitoring at iron ore concentrators, in Proceedings Iron Ore 2013 , pp 303-308 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By W. C. Phalen

During the search for deposits of soluble potash salts in the United States, carried on by the United States Geological Survey, much information was collected on the salt resources and industry of the United States. The more important features of the information thus gathered, compiled, and digested may be classified under five headings, as follows: 1. Geology of the salt deposits of the United States. 2. Theories relating to the origin and formation of salt deposits. 3. Chemical composition of saline materials in the United States, principally rock salt and natural and artificial brines. 4. Statistics of salt production in the United States. 5. Technology of salt production. The first four items are not discussed in this report, but their treatment will comprise a separate report published by the Geological Survey,a which will supplement this report, relating to salt-making processes, and will describe comprehensively the salt resources of the United States. Persons desiring a copy of that report should apply to the Director of the United States Geological Survey, Washington, D. C.

Jan 1, 1917