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By Tony Walsh

Timely disclosure of information germane to the taking of investment decisions makes an essential contribution to ensuring the growth, efficiency and integrity of our capital markets. It is a core contributor to the maintenance of fair, orderly and transparent markets. The communication of relevant and comprehensible information to the investor plays a vital part in fostering investor confidence, thereby building depth and liquidity in our market. Australian Stock exchange Limited ("ASX") has had and continues to have a rewarding partnership with the mining industry to develop and recognise reporting standards, the JORC Code. This allows ready comparability and investor understanding of the mining investment vehicle. ASX's mining market has been successful because of the high reporting standards in the JORC Code and the high standards of professionalism and the intellectual capital that has been built up among the participants - the mining professionals, brokers, analysts, mining investors, professional advisers and the market operator. The balance of knowledge and understanding among these participants combined with the competition for capital, contributes to the standards for our mining market in a way that the market operator simply cannot replicate by market rules alone.

Jan 1, 2003

By R. Lawrence

Mineral property valuations to be used for Canadian securities regulatory purposes must comply with CIMVal1. The technical basis for a CIMVal report is the same as that required for a technical report that complies with NI 43-1012. NI 43-101 describes the content to be covered in a technical report, while also covering other requirements, one of which is that the report should be based on a property visit. CIMVal is based on five tenets that the valuator must follow: ? Materiality. ? Independence. ? Transparency. ? Competence. ? Reasonableness. Upon its adoption by CIM Council in 2003, it was hoped that the new CIMVal code would be adopted without change by the several Canadian regulators.

Jan 1, 2011

By T. J. Batchler

Deformable materials are sometimes added to ventilation stopping constructions to prevent damage caused by convergence in coal mines. However, adding deformable materials can significantly reduce the capacity of a stopping to resist transverse loading. As part of its mining health and safety program, the National Institute for Occupational Safety and Health (NIOSH) has conducted research on the effect of various materials with different deformation properties on the transverse loading capability of a stopping wall. Based on a three-point hinge method of failure, a half-wall method of testing in the NIOSH Mine Roof Simulator was used to simulate full-scale wall behavior. This simulated the fracture initiation and eventual failure of the stoppings from transverse loading. The impact of the modulus of elasticity of various deformable materials was examined in this study. A polystyrene foam block with a low modulus of elasticity, which is commonly used as a deformable material, was shown to degrade the transverse load capacity of the stopping by as much 95%. Other materials with higher modulus of elasticity preserved more of the transverse load capacity of the stopping, but were not able to absorb as much convergence. This paper presents the results of a parametric study that quantifies the impact of various deformable materials in block stopping construction under transverse load conditions. Disclaimer: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

By Steven Norris, William Moler, Michael Cole, Patrick Doig, Debi Lewis, Craig Pyle, Matthew Crow

The recently completed Lower Northwest Interceptor Program (LNWI) in Sacramento, California comprises, ten pairs of micro tunnels totaling 4,369 m (14,417 ft),three horizontal directionally drilled bores totaling 956 m (3,154 ft), and two large diameter tunnels under the Sacramento River totaling 1,198 m (3,953 ft). This paper briefly summarizes surface and subsurface conditions, and planning and design considerations. It then goes on to describe problems encounterd with each trenchless crossing, as well as lessons learned with respect to shaft construction, ground control at shafts during tunnel break-in and break-out, frac-out and heave, settlement, obstructions, coordination with permitting agencies, and application of geotechnical baseline reports.

Jan 1, 2007

By Fouad Faraj

For every blast pattern, zones of unique material types need to be classified before mining. Most material types can be summarized into different kinds of ore and waste. Blocks generated from blasthole assays are too small to be selectively mined, so areas with a single material classification meeting the mine’s selective mining unit must be defined. Current industry standard practices are to manually draw ore/waste dig limits, but this process is subjective and results in quantities of dilution and ore loss that can be improved upon to enhance the profitability of mining operations. In this study, two weeks of production data from a homogeneous copper (Cu) porphyry and heterogeneous manto-type Cu deposit were used to assess the variability in the hand-drawn dig limits of 20 geologists, mining engineers and ore control specialists, which were compared with the optimal ore/waste delineation. The profit for 20 distinct hand-drawn dig limits for the homogeneous mine varied by 3.7 percent, from $10.5 million to $10.9 million, averaging at $10.8 million. The percentage was nearly double for the more heterogeneous mine at 5.9 percent, from $17.9 million to $19.0 million, averaging at $18.6 million. Using the optimal ore waste delineation, the profit increased to $11.0 million (1.9 percent increase) and $19.3 million (7.0 percent increase) for the homogeneous and heterogeneous deposit, respectively. The natural variability, diggability requirement and selectivity are identified as the main drivers of ore loss and dilution. Recommendations are provided for reducing the subjectivity in manual hand-drawn dig limits by integrating dig limit optimization algorithms as a tool to assist practitioners.

Oct 1, 2024

On Nov 1, 2007 House Resolution 2262 ? The Hardrock Mining and Reclamation Act of 2007 ? was passed by the U.S. House by a vote of 244-166. HR-2262, among other things, would impose a 4-per-cent royalty on existing mines with commercial production and an 8-percent gross royalty on all new claims. Not surprisingly, this possible new law was one of the hottest topics of discussion at the Northwest Mining Association?s conference that this year returned to Spokane, WA for its 113th annual meeting on Dec. 3-7. More than 1,800 delegates attended the conference that was held under the banner theme of ?Mining ?. For today and tomorrow.? Northwest Mining Association executive director Laura Skaer was one of many speakers during the three-day conference to respond to the threat to the industry posed by HR-2262 with a presentation titled ?Potential changes to the 1872 Mining Law.? In the presentation that she first unveiled at the Alaska Miners Association?s convention and trade show on Nov. 8, Skaer laid out a comprehensive list of problems with HR-2262. In addition to the association?s obvious concerns about the proposed royalty, Skaer noted that the bill includes a mine veto provision that would allow the Secretary of the Interior the authority to deny an operations permit to a project if the secretary determines that the operation would cause undue degradation to public lands and resources. Potential massive withdrawals from mineral entry are also included in HR-2262. Among the lands that could be off limits to miners under HR-2262 are wilderness study areas, areas of environmental concern and 23.6 hm2 (58.5 million acres) identified as Roadless Rule. States, political subdivisions and Indian Tribes would also have more authority to withdraw lands, she said. To combat the proposed changes, Skaer made 10 trips to Washington D.C. on behalf of NWMA members in 2007. In her presentation at the annual meeting, she also objected to provisions that include no life-of-mine permits and uncertain permit renewals and new and duplicative environmental standards that she said are vague, ambiguous and inconsistent with current federal and state environmental laws. Debra W. Struhsacker, an environmental permitting and government relations consultant, also spoke on the issue of HR-2262 with a presentation titled ?The House mining law bill ? Rip van Winkle is back ? and he?s meaner than ever.?

Jan 1, 2008

By B. J. Arnold

Utility coal specifications usually contain a requirement for a maximum moisture content in order to prevent coal handling problems and to minimize evaporative losses in the boiler. As most coal cleaning processes are water-based, dewatering and sometimes thermal drying steps are required to meet moisture specifications. Screens are often used for dewatering, with centrifuges and filters used to further reduce moisture in many cases. Algorithms to predict the performance of commercial dewatering devices were developed for the Coal Cleaning Simulator running under Aspen Plus? during a project sponsored by the U.S. Department of Energy and the Electric Power Research Institute. These algorithms include calculations for size degradation in the devices and fines loss to effluents, where appropriate, and a calculation for moisture content of the product based on particle size and specific gravity distribution. This paper discusses the algorithm for coarse and fine coal centrifuges and gives comparisons between predicted moisture and solids loss and published moisture and solids loss values for various particle size ranges.

Jan 1, 1996

By J. L. Yordan, J. Kortmeyer, I. Yildirim

Talc is used to remove stickies from pulp during paper recycling processes. It is well known that the interaction is controlled by the surface chemistry at the talc/water, sticky/water and talc/sticky interfaces. If the interfacial tensions are known, one can calculate the free energies of interaction and hence predict whether the stickies can be removed by talc. In the present work, the surface tensions of several different talc samples were determined using the acid/base theory. The information was then used to determine appropriate interfacial tensions, which in turn were used to determine the free energy of interaction between talc and stickies. It was found that the calculated free energies are much more negative than those between the stickies and other minerals such as calcium carbonate, bentonite clay and kaolin clays.

Jan 1, 2002

By R. A. Jankowski

Laboratory tests were conducted to evaluate the silica collection efficiency of flooded-bed scrubbers using six different filter panel designs at two operating velocities. Test results indicated that reductions in filter density negatively impacted respirable dust collection. Silica collection efficiency for the least-dense filter was as much as 33 % lower than the collection efficiency of the most-dense filter. At the low operating velocity, the least-dense filter allowed more than 40% of the respirable silica dust in the scrubber intake air to pass through the unit and back into the mine environment. Operation of the scrubber at the higher test air velocity increased silica collection efficiency regardless of the filter panel tested The density of the filter panels also impacted the quantity of air moved through the scrubber, with higher-density filters reducing scrubber airflow. For each filter, the relationship between dust-collection efficiency and air-moving capacity must be considered to determine the overall effectiveness for each mine application.

Jan 1, 2000

By W. L. Chen

In the United States hydraulic cyclones have been used for thickening, classification and cleaning in coal preparation plants for many years. The cleaning cyclones presently in use are based on using a "heavy medium", such as a fine magnetite and water pulp. The latest addition to cleaning cyclones is the one which uses ?water only?, or simply called "Hydrocyclone". Just as was the heavy medium cyclone, the hydrocyclones were originated in the Netherlands (1, 2). Plants using hydrocyclones were built in Europe (3) and test plants were erected in Canada (4, 5, 6) and India (7). Roberts and Schaefer Company has built four plants using hydrocyclone circuits. One additional plant is in the process of construction.

Jan 1, 1965

China has made great progress in thick coal seam mining, commonly characterized by longwall top-coal caving mining and single-pass longwall mining with a large cutting height. At present, the maximum mining thickness of longwall top-coal caving reaches 20 m while that of single-pass longwall mining approaches 8.8 m. The top-coal caving–related technologies have significantly improved the mining efficiency of thick coal seams and have also made a great contribution to the centralized underground mining of coal. Thus, the number of underground coal mines is greatly reduced in China. However, due to the increase of the mining height and the changes in mining operations, the overburden movement caused by the mining of thick coal seams is more intense, and the influence scope is larger, which brings a series of new problems on ground control of longwall faces. In order to enhance ground control and improve the mining efficiency of thick coal seams

Jul 28, 2020

By D. C. Hatch

At the MacIntyre Development of the Titanium Division of National Lead Company a magnetite-ilmenite ore together with gabbro-anorthosite waste is mined from an open pit by shovels and trucks. The ore from the pits is trucked to ore stockpiles for blending ahead of the crusher and to free the mine from crusher delivery schedules. The ore stockpiles are blended to yield a 16.5 to 17.0 % TiO, crusher feed. This requires mining on an assay cut-off rather than a visual grade cut-off. Highly mineralized ore runs from 20 plus % TiO2 and 30 plus % Fe to 15 % TiO2 and 40 plus % Fe as the ratio of ilmenite to magnetite changes. There are three major ore types in the present pit with magnetite ratios varying from about one to one up to three times as much magnetite as ilmenite. Ilmenite and magnetite together liberate from gangue down to about 10 mesh and this is the basis of the magnetic cobbing. Below 10 mesh the ilmenite and magnetite start to separate and ore cobbing pulleys will not hold the ilmenite.

Jan 1, 1968

By Russell W. Hunt

The cave man of ages past took his wife-and family from the cave pointing to a fire he had built and beating on his breast said, "Look what I have done". Today man is taking his family back to a cave saying, "Come enter in because of what I have done". At the close of World War II Germany said if they had gone underground one year earlier with more of their operations, the war could have lasted four years longer with perhaps much of Britain devastated. The protection of the home front no longer rests with the soldier in actual combat. The battle will be won at home with the most careful kind of protection against missiles. After Nagasaki-Hiroshima Sir Winston Churchill said in substance "Up to now the Almighty has mercifully withheld from man the knowledge of these terrible weapons of destruction."

Jan 1, 1959

By Joseph R. Hatch

Previous studies of the Thompson and Temperly ore bodies show alteration aureoles in the Middle Ordovician host-rock limestones, dolomites and shales extending laterally as much as 60m from the ore. Thickness, texture, carbonate and clay mineralogy, major-, minor-, and trace-element contents; and carbonate carbon and carbonate oxygen Isotope compositions of the host rocks all have been significantly altered by hydrothermal processes. Organic geochemical analyses of samples from the basal 8-cm-thick carbonaceous shale bed and immediately overlying limestone bed of the Quimbys Mill Member of the Platteville Formation, collected from within the ore, the alteration aureole, and the unaltered country rock show: 1) solution of carbonates and residual concentration of organic matter, 2) decreases in the volatile (Si) and pyrolytic (S2) hydrocarbon yields In samples of the basal shale from within the ore, 3) decreases in the relative amounts of the lower molecular weight (<nC25) saturated hydrocarbons in samples from the ore, and 4) no changes in either the organic carbon isotope composition or the Rock-Eval or biomarker thermal maturation Indicators. In light of the 125-170°C depositional temperatures documented for the early marmatitic sphalerltes in these deposits by fluid Inclusion studies, the lack of thermal alteration of the organic matter suggests a relatively short mineralization episode, a conclusion supported by the relatively simple sphalerite band stratigraphy. The decreases in the volatile and pyrolytic hydrocarbon yields for shale samples from the ore supports a model for mineral deposition which obtains sulfide through reaction of brine sulfate and indigenous organic matter.

Jan 1, 2013

By Dale K. Fields

With today&apos;s technological advances in mineral processing equipment, there is an increasing demand for accurate system control. This can only come about through representative sampling. The purpose of this paper is to guide you in the selection of sampling equipment and outline design parameters for the cutters used in dry and wet sampling without adding redundant mathematical probability formulas to your files. Special attention will also be given to the equipment used in conjunction with samplers and sampling systems, such as feeders, crushers, chutes, launders, and controls.

Jan 1, 1979

By K. A. Natarajan

The utility of yeast, Saccharomyces cerevisiae, in the separation of quartz from hematite is demonstrated. Yeast cells, as well as their metabolites, functioned as flotation collectors, depressants or flocculants and dispersants for hematite and quartz. Interaction between yeast and the above minerals resulted in significant surface chemical changes, rendering quartz surfaces hydrophobic and hematite hydrophilic. Mineral-specific extracellular proteins and exopolysaccharides were secreted by yeast cells when grown in the presence of quartz and hematite, respectively. Quartz could be efficiently separated from hematite through microbially induced flotation and selective flocculation.

May 1, 2012

By J. H. Kim

Since the Hardy Cross numerical algorithm was applied to the solution of mine ventilation networks, there have been numerous developments in ventilation network analysis procedures. The Newton-Raphson method, the linear theory method, and the second-order approximation method are three of the additional approaches that have been applied. The efficiency of a ventilation network analysis procedure depends not only on the method of solving the system of equations derived from ventilation networks, but also on the method of deriving the equations through selection of the meshes. This paper investigates the impacts of three mesh selection methods on the efficiencies of four ventilation network procedures. The minimum-resistance spanning tree method is the most popular procedure for selecting meshes. The shortest-path method was suggested by Epp and Fowler (1970) for improvement of the Newton-Raphson method. The minimum-resistance-path method is suggested here as the third method of selecting meshes. The effects of these three methods on the Hardy Cross method, the Newton-Raphson method, the linear theory method, and the second-order approximation method are analyzed in this paper. These network analysis methods have been summarized in the paper by Kim and Mutmansky (1991).

Jan 1, 1992

By D. Jacobson

There are many different machine setup parameters and variables that affect the production of cone crushers in a mineral processing plant. One of these variables is the eccentric speed at which the cone gyrates. In June 2012, pilot tests were conducted on a 200 hp high speed cone crusher to determine the production and operating conditions over a wide spectrum of eccentric speed. Every plant will have variations in the ore characteristics and feed rates throughout the life of the mine, and at times throughout a single shift of operation, which result in non-optimal use of the crushing energy and inconsistent process control. For high speed cone crushers, the crusher will exhibit a different capacity, power required, and discharge size distribution as the speed ranges over the design limits of the machine. This study documents the measured variation in production and energy efficiency both when the crusher was ran at full capacity as well as when the feed to the crusher was not sufficient to run at full capacity. Overall, the results match theory and the capacity and power fluctuated by 25% and 17%, respectively, over the speed range when operated full while there was an overall trend of slightly coarser discharge size distribution as the speed decreased. The results with the fixed feed rate were more telling, as the crushers had 4-14% higher production when making a theoretical minus 12.5 mm product when operating at the optimal speed as compared to the worst speed in the ?typical? speed range for this application. Secondary analysis of the fixed tonnage testing also showed that the power draw was more consistent with lower magnitude spikes at the higher speeds (higher cavity level), as on average the standard deviation of the power draw increased from 7% to 18% and the peak power spikes from 20% to 48% over the speed range tested. The findings lay groundwork for more efficient plant design. Varying the speed of the crusher can be used to tune the crusher speed during commissioning, adapt to changing ore conditions over long periods of time, or be used as a dynamic input into an advanced control system. Each action above would serve to make the crusher(s) more productive and more energy efficient, and would also have mechanical benefits for the machine. Key Words: cone crusher, ore reduction, process control, crushing efficiency

Feb 27, 2013

By C. E. Jordan

The Bureau of Mines has investigated the fundamentals of fatty acid/fuel oil conditioning for improved flotation selectivity. Both conditioning time and intensity can provide optimum flotation selectivity as well as good recovery. Traditional conditioning seeks to optimize conditioning parameters with subsequent recovery of the hydrophobic mineral. In the fatty acid/fuel oil system many silica gangue particles are also rendered hydrophobic by the flotation collector. Fundamental studies have shown that particle-particle collisions transfer the collector reagents selectively to the mineral surfaces with the highest affinity for the reagent. This mechanism deactivates the gangue particles while increasing the collector reagent loading on the selected mineral. The degree of this transformation is directly related to the number of particle-particle collisions which can be controlled through conditioning time or conditioning mixing intensity.

Jan 1, 1995

By B. E. Davis

A fundamental study of the mechanisms involved in the conditioning of coarse Florida phosphate has led to some interesting discoveries. Studies by the Bureau of Mines have shown that conditioning time and mixing intensity greatly affect the grades and recoveries of the phosphate minerals and quartz in the rougher concentrate. In particular, as the conditioning time or mixing intensity increased, the phosphate recovery remained constant while the amount of quartz floated decreased. This phenomenon is contrary to conventional wisdom and could lead to a more efficient coarse flotation circuit.

Jan 1, 1993