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By J. O. Voigt

No major changes took place in the salt industry during 2004. No new uses of salt appeared and only localized supply disruptions occurred. Many salt producers reported slightly increased salt sales and profits for the year. In the United States, about half of the salt supply is produced as brine, by solution mining, and is used by the chemicals industry. One-third of U.S. salt is produced as rock salt by 14 underground mines. The remaining two production techniques, each with less than 10 percent of the total tonnage, are vacuum-pan-evaporation for refined, food-grade salt, and solar pond crystallized salt.

Jan 1, 2005

By Charles Ronkos, Jeffrey Edwards, Brian Brodsky

The Marlin gold-silver deposit is in western Guatemala, 15 kilometers south of a major transform fault that separates the North American and Caribbean plates. A district-scale, northwest-trending graben controlled deposition of a greater than 1200 meter thick upper Tertiary quartz latite to rhyolite volcaniclastic sequence. These volcanics were subsequently intruded and unconformably overlain by a small intermediate, latite to andesite, volcanic complex. Classic low-sulfidation, quartz-calcite-adularia veins and stockwork formed a 2.2 million ounce gold deposit, in association with late-stage andesite dike swarms, along a west-northwest striking normal fault on the eastern flank of the volcanic complex.

Jan 1, 2005

By P. Roghanchi

The Rock Mass Rating (RMR) system is an internationally recognized classification system that can be used for preliminary ground control design. The RMR system assigns quantifiable values to predefined classified parameters of a rock mass. Assigning a single value rather than a range to each parameter is a source of uncertainty, however, assigning a single value can be useful for further studies related to RMR ratings. Fuzzy systems are being used in an increasing number of application areas where linguistic rules are used to describe the system. In past decades, fuzzy systems have been successfully used in geotechnical and mining engineering problems to cope with uncertain data as well as with vagueness. In such scenarios, linguistic rules and rating-based classification of rock masses have always been questionable. The objective of this study is to apply fuzzy set theory to the RMR classification system. The fuzzy system proposed in this study is specified for weak and very weak rock masses (RMR<50) based on data collected from Nevada gold mines where 68% of RMR data is in the ?poor? and ?very poor? classes. In this approach, a Mamdani fuzzy algorithm has been constructed to evaluate basic RMR89 rating for the ?wet condition.? Comparison between basic RMR89 and fuzzy RMR shows the fuzzy RMR system is valid to predict RMR from the discrete rating of each input parameter.

Feb 27, 2013

By J. Darlington, A. K. SenGupta

Water-swellable layered silicates, namely, the smectite clays can remove suspended materials (called herein as debris) and metal ions from aqueous streams. The present study shows that the flocculating and metal extracting abilities of smectite clay-based flocculants can be enhanced when these clays are used in conjunction with a specific anionic polymer. Such performance enhancement is attributed to the following: i) the clay-dispersing ability of the polymeric additive, that would translate into an increase in the clay-surface area available for the attachment of the debris particles onto the clay particles; ii) the possibility of dispersant-to-coagulant transition of the polymer during the later instants of the treatment process, as a result of reduction in solvency of the wastewater for the polymer due to the release of cationic species from the clay-based flocculant solids; iii) metal-complexing ability and adsorption properties of the polymer.

Jan 1, 2002

By V. I. Lakshmanan, Dan A. Mackie

Traditional vat leaching methods have had limited success, primarily due to the high cost of loading and unloading the vats. In general, such batch methods are labor-intensive and costly. Heap leaching has emerged as a viable, low- cost alternative, but low recoveries, normally in the 70% range, offer opportunities for improvement. Also increased regulatory guidlelines for effluent and spent heap leach pads disposal offer potential for alternative methods. The Mackie Vat Leaching Jig (MVLJ) has had its incubation at Ortech International, where bench scale through pilot scale testing continues. Design developments and testwork over the past two years indicate that the time may be right for field trials.

Jan 1, 1990

By Daniel Tao, Jike Qiao, Hao Ren, Feifei Ji, Gonglun Chen

The floatation of niobite was studied using a number of collectors at various dosages and solution pH’s. Octyl diphosphonic acid was found to be an effective collector for niobite flotation with good selectivity. A flotation recovery of 91.2% was obtained with 140 mg/l octyl diphosphonic acid at pH’s less than 5.0. Infrared absorption spectroscopy (IAS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the interactions of niobite with octyl diphosphonic acid. Species distribution diagram of octyl diphosphonic acid and niobium species was used to elucidate the flotation behavior of the mineral with octyl diphosphonic acid. A chemical adsorption mechanism of niobite with octyl diphosphonic acid was proposed. Keywords: octyl diphosphonic acid, electrokinetic measurements, niobite flotation, XPS.

Jan 1, 2005

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

Incident investigation is of utmost importance in most high-risk industries and is often used to improve organisational safety. This study was undertaken to examine the content of past incident investigation reports to determine the effectiveness of the incident investigations. The study uses a semi-quantitative method to assess the effectiveness of incident investigations in the Ghanaian mining industry by evaluating the quality of past investigation reports. The assessment tool consists of five elements with several indicators and rating scales for assessing the quality of an investigation report as a measure of the effectiveness of the investigation. The method was applied to 304 investigation reports of three Ghanaian large-scale gold mines, and the results correlated with incidence rates of the mines to determine if any relationship existed. The results showed that the mines differ significantly in the quality of their investigation reports, suggesting differences in the effectiveness of their investigations. In addition, the incidence rates of the mines negatively correlated with some elements of the assessment tool. In general, the method was found useful and revealed areas where improvement is needed.

By W. K. Hitchcock

Hydrogen is regarded as being a high temperature indicator of spontaneous combustion. It is currently used in underground coal mines to detect advanced heating?s. Previous work has mostly consisted of small scale tests with high air flow to mass ratios. A large-scale test rig has been used to investigate the gas indicators of coal self-heating. In particular, the relationship of gas evolution, the location of its evolution and the temperature at which it is evolved has been examined. It has been found that there are two distinct zones of hydrogen production: one at the hot spot and the other in an oxygen deficient moist zone downstream from the hot spot which is at a relatively low temperature of approximately 100°C. This has implications for the interpretation of mine atmospheres.

Jan 1, 2009

By Satid Therdkiattikul, Donald A. Dahlstrom

By oxidizing the pyrite matrix through biological leaching of precious metals ores or concentrates, better than 90% recovery of gold and silver is achieved. The paper develops three precipitation processes that eliminates arsenic and all other toxic elements in the resulting liquor after the biological reactors. In addition, the precipitates are highly crystalline and resist resolubilization. The latter must be tested for at least six months by EPA test procedures. The three systems are temperature (must be at least 120°C or higher) lime or limestone. A continuous pilot plant was employed for all three systems and complete recommendations are given to optimize Fe/As molar ratio, reaction kinetics (detention time) pH, temperature, wt % feed solids as well as resultant reagent consumption based upon continuous operation.

Jan 1, 1995

By J. L. Hoover

The goal of the drill bit consumption study was to develop an equation(s) based on various components that affect bit drill wear and use the equation(s) to estimate the consumption of bits during production drilling. Drill bit data from various geographic locations were compiled and used to develop linear regression equations using the Microsoft Excel Software. Multiple drill bit consumption equations were developed and statistical analysis was used to verify the accuracy of those equations. The equations will allow mining companies to more accurately forecast drill bit consumption when evaluating new mine properties. This capability becomes increasingly beneficial to forecasting as the cost of consumables increases.

Jan 1, 2012

By C. Ottergren

A process does not have higher capacity than what can pass through its bottleneck. Acknowledging this, and with the goal to optimize production at a minimum investment, one can use existing equipment, modify the process flow and make a few strategic capital investments. Automatic setting regulation is a technology that allows balanced crusher performance matching minute changes in feed material characteristics. The system makes it possible to utilize the crushers fully at all times. It also continuously and completely compensates for manganese liner wear.

Jan 1, 1999

Recent accelerated exploration efforts in southwest China have progressively quantified the vast phosphate resources in the Yunnan Province. To date, according to Chinese geologists, potential reserves in the province may be on the order of 4 Gt, which would equal the entire US reserve base. Development of this vast reserve is underway at two sites located 60-70 km southwest of Kunming, the provincial capital of Yunnan. The first, the Kunyang open-pit phosphate mine, produces an estimated 1.5 Mt/a of 22-30% P20,5. The other project located north of Kunyang is the Haikou mine, which the Chinese consider a possible 2.0-Mt/a operation. Because average ore grades run 3% less than those of Kunyang, beneficiation will be necessary. While the latter project has been initiated on a small scale, it is basically still on the drawing board. Brown and Root and the US Bureau of Mines are assisting on the project. Both operations are under the direction a regional administration which reports to the Ministry of Chemical Industries in Beijing. Combined production from both mines could represent some 70% of China&apos;s future productive capacity. Ore reserves in the region are estimated at 400 Mt by local officials. Geology of the District The phosphates are considered Cambrian in age and rest on a Precambrian dolomite. The Indian Ocean, Chinese geologists say, may have been the original source. The line of deposition stretches on a trend from Vietnam in the southwest, through Yunnan, into Sichuan Province to the northeast. Because the area is considered very stable from a geologic viewpoint, large quantities of phosphate have been deposited and large outcrops are known to occur everywhere in the province, according to Chinese sources. The Kunyang and Haikou ore bodies are thought to be two wings of an anticline with the former the southern portion, and the latter the northern portion. Each ore body strikes on an east-west axis. While there are many localized phosphate operations throughout the province, the Kunyang mine is the premium producer. Kunyang&apos;s Mining Development The Kunyang open-pit mine was opened in 1966. During the early years, operations were considered somewhat disorganized. Systematic mine planning and normal operations were not initiated until just two years ago, according to mine management. In 1979, Kunyang finally reached its design capacity of 1.5 Mt/a. The ore body consists of two phosphate beds separated by a band of shale. The top layer of phosphate varies from 4 to 8 m, averaging 6 m. The middle shale layer is 2 in. The third layer, which is not as rich as the top, is approximately 4 m. To further complicate matters, the ore dips 15° to the south over a strike length that is currently undefined, but believed to be

Jan 3, 1980

Start with your assessment of the minerals business —domestic mining as well as operational and consulting perspectives. As a third generation miner, I have been living the mining business for as long as I can remember. I have watched commodity prices produce boom and bust cycles in places like Price, Utah (coal), Douglas, Arizona (copper) and Eureka, Nevada (gold). It is unsettling to see how our industry has fluctuated, but it always seems to rebound if you can stick out the down cycles. However, our most recent dip in the cycle was, in my opinion, characteristically and permanently different. In the past, when prices went south, people hunkered down and waited out the cycle until things came back, much the same as they had every other time. Not this time. This time, we saw a consolidation of the industry in proportions never seen before. Mega-mergers like Exxon-Mobil, Phelps Dodge-Cyprus and Newmont-Normandy have changed the complexion of our industry forever. And that is true not just of the mining companies; it happened across the supporting business lines as well. As a midsized niche engineering and environmental service provider to the mining industry, companies like mine are few and far between these days. The lean cycle saw many of the small and midsized providers get gobbled up by consulting giants like URS and TetraTech. The mentality of a mega-company, whether a commodity producer or a goods or service provider, is different than that of their small- and medium-sized counterparts.

Jan 1, 2005

By S. M. Carpenter

In response to the FY2008 Consolidated Appropriations Act (H.R. 2764; Public Law 110?161), the United States Environmental Protection Agency (USEPA) issued the final Mandatory Reporting of Greenhouse Gases Rule (MRR). The rule, signed by the USEPA Administrator, Lisa Jackson, on September 22, 2009, requires reporting of greenhouse gas (GHG) emissions from large sources and suppliers in the United States, and is intended to collect accurate and timely emissions data to inform future policy decisions. The MRR will go into effect on January 1, 2010, and a report of the total emissions for calendar year 2010 will be due to the USEPA by March 31, 2011. Under the final MRR, suppliers of fossil fuels or industrial greenhouse gases, manufacturers of vehicles and engines, and certain facilities that emit 25,000 metric tons or more per year of GHG emissions are required to submit annual reports to the USEPA. The gases covered by the rule are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFC), perfluorocarbons (PFC), sulfur hexafluoride (SF6), and other fluorinated gases as outlined in Table A-1 of Subpart A of the MRR, which is also provided in Appendix A of this report.

Jan 1, 2011

By Jordan Scheremeta, Sudhir Tripathi, Mahfooz Alam

Injection leaching can improve leach ore recovery by displacing retained solutions, enhancing ore wetting, and creating new flow paths for efficient solution collection. This paper presents a method to assess the feasibility of injection leaching in finer-grained, potentially contractive ores (from a geotechnical slope stability perspective) using limit-equilibrium (LE) slope stability analysis and static deformation modeling. LE models were carried out by assigning peak undrained strengths to the heap leach ore material, and modeling the excess pore pressure induced during the injection leaching process using spatial function in Slope/W. Static deformation modeling was completed using the software Fast Lagrangian Analysis of Continua (FLAC) to evaluate the potential for deformations due to the excess pore pressures induced during the injection leaching process. A constitutive model was used to represent the geomechanical behavior of the leached ore material, which enables the prediction of deformation and potential stability issues resulting from excess pore-pressure induced during injection leaching process. The two-pronged approach provides a practical method to assess geotechnical impacts and guide data-driven decisions in injection leaching operations.

Feb 22, 2026

By T. R. Ellis

Australia’s mineral valuation code continues to evolve, while mineral valuation standards are also being written for Canada and Southern Africa. The author is leading a task force for writing the extractive industries addition to the International Valuation Standards. Meanwhile, the International Accounting Standards Board is continuing the development of an extractive industries addition to its International Financial Reporting Standards, with an emphasis on valuation reporting. This paper analyzes the need, content and ownership for a U.S. minerals appraisal standard in the context of both these developing international standards and also existing U.S. regulations and appraisal standards. The author provides many questions for research and debate.

Jan 1, 2003

By R. J. R. Cornelissen

The elimination of the incidence of silicosis in employees in industries such as mining and pottery is an ongoing international initiative. After many decades of industrial activity in these industries and many dollars spent on preventative measures, silicosis is still occurring. The exposure-prevention measures taken so far have certainly improved the working environment dust concentrations; however, the illness is still regularly diagnosed in workers. More funding is needed for interventions to improve working conditions. Many aspects of dust prevention and suppression will be researched and exposure assessment methodologies and equipment will need to be reviewed for the purposes of improvements in effectiveness. This paper presents results from laboratory tests carried out on gravimetric sampling pumps and cyclones. It highlights the erratic flow produced by gravimetric pumps of three different manufacturers who claim their respective pumps are equipped with flow stabilisers. The standard BS EN 1232:1997 is used as a basis for the tests. A method, albeit impractical for fieldwork, is shown for the elimination of the pulsation in the flow. This method serves to prove the method and protocol used in this study. The pressure loss caused air-flow resistance of cyclones is measured. The air inlet aperture size of cyclones is measured. The large discrepancy in the two criteria between individual cyclones is shown. The paper concludes that all the pumps tested failed the prescribed limits of BS EN 1232:1997 regarding the pulsation of the gravimetric sampling flow. The difference in flow characteristics of the cyclones, together with the erratic flow produced by the pumps, throws into question the accuracy of the exposure assessments. It is suggested that substantial resources be channelled towards solving these flow problems in parallel with measures taken to reduce exposure. In principle, the accurate assessment of exposure and dust concentration levels is a prerequisite for effective management of the problem of silicosis.

Jan 1, 2009

By E. M. Spokes

Starting in 1980, a committee of the National Research Council studied the question of why some underground coal mines are safer than others and what could be done to improve the ones with poorer performance. The results indicated that safety is improved by management commitment to safety, by cooperation between labor and management on safety matters, and by quality training of employees and managers. Younger miners have higher accident frequencies, but are less likely to be killed or permanently disabled by a lost-time accident. Methods for improving safety performance are proposed.

Jan 1, 1987

By Jaisen Kohmuench, Michael J. Mankosa

Flotation has long served as the foundation for sulfide mineral recovery. As ore grades decline, however, this traditional approach is being pushed to the limit. Nowhere is this more evident than in the challenge of recovering coarse, partially liberated particles — an area where conventional flotation systems typically underperform due to excessive turbulence. As a result, valuable coarse minerals are often lost to tailings. Fine grinding has become the default solution, although with the added burden of higher operating costs and more challenging tailings disposal. To address the challenge of coarse particle recovery, Eriez developed the HydroFloat, a technology that uses a novel fluidized-bed approach to extend the upper particle size range of flotation significantly. The HydroFloat can recover particles exceeding 0.5 mm in diameter with a sulfide surface expression as little as 2 percent. Coarse particle recovery allows for optimization of comminution circuits for coarse gangue rejection before fine grinding. A substantial increase in overall tailings particle size provides higher water recovery due to improved drainage and allows for consideration of a dry, stacked tailings option instead of a tailings dam/impoundment. The technology’s transformative potential has not gone unnoticed. In recognition of its impact, Eriez was honored with the 2024 Robert E. Murray Innovation Award, commonly referred to as the Murray Award, by the Society for Mining, Metallurgy & Exploration. This prestigious award was established in 2017 to recognize organizations that advance the mining industry through the implementation of technical innovation. The HydroFloat stands as a fitting example of how creative thinking and industry collaboration can solve long-standing technical challenges.

Oct 1, 2025

By L. Lipsett

"Human rights can contribute to sustainability in the mining sector, both in theory and in practice. Both human rights and sustainability share a common concern to improve economic prosperity, environmental health and social equity by avoiding negative impacts and conflict, as well as by engaging with and empowering affected communities. Globally, there is an emerging consensus that companies have a responsibility to respect international human rights standards. Respecting human rights means that mining companies are responsible to ""do no harm"" to the people and communities affected by their operations. After a discussion of the Protect, Respect and Remedy framework for business and human rights, this paper illustrates some examples of how international standards for human rights and sustainability interacted in a recent assessment of Goldcorp&apos;s Marlin Mine in the Western Highlands of Guatemala. The final section explores how human rights should be integrated into broader policies and procedures for corporate sustainability. This includes integrating human rights into ESIA processes, legal compliance, corporate governance and grievance mechanisms. Pressures on mining companies to respect human rights will not disappear; therefore, a proactive and integrated approach to human rights is a fundamental component of a broader strategy for sustainability"

Jan 1, 2011