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By M. Karmis

Subsidence planning and control must be an integral part of mine design in order to minimize the economic impact of underground mining on the surface. Pre-calculation of surface deformations which may cause damage to surface structures must be performed and dam-age criteria must be established, if the response of structures to such movements is to be determined and the extent of damages to be assessed. In this paper the Surface Deformation Prediction System (S.D.P.S.), which can be used to predict accurately the vertical and horizontal parameters of surface movements due to underground mining, is discussed. The Subsidence Response Modeling Program (S.R.M.P.). which can be applied to evaluate the response of buildings to subsidence-induced movements, is also reviewed. Finally, an example is presented demonstrating the applicability of these techniques for subsidence design and control.

Jan 1, 1990

By J. Rostami, J. Brune, S. Slouka

Respirable dust poses long-term health issues to personnel working in mining and civil projects where mechanized mining and tunneling machines are used for hard rock excavation. Machines, such as longwall shearers, roadheaders, or continuous miners, use consumable picks to cut rock. However, rock dust is generated in the work environment each time the pick tip contacts the rock surface. Additionally, the generated dust can be reintroduced into the air further down in production, such as at transfer points. The purpose of this study is to characterize respirable dust particles generated at the pick tip at two stages of pick wear: new and moderately worn. Understanding dust characteristics in terms of concentration, size distribution, and particle shape throughout the life-cycle of the pick will provide a basis to mine and tunnel operators for changing out picks to mitigate dust generation at the source. This paper discusses the dust characteristics generated from preliminary full-scale cutting tests in a laboratory of an igneous rock block cut with conical picks at new and moderately worn levels of wear. The moderately worn pick generated a size distribution that favored smaller particle sizes compared to the new pick. The moderately worn pick also generated more overall dust, as the concentration level in mg/m3 was over double the amount of the new pick. Lastly, both picks generated particles that had similar aspect ratios and roundness measures.

May 18, 2022

By Marvin P. Barnes

An attempt has been made to compile and code geologic data relating to twenty of the major porphyry copper districts of North America in such a manner as to permit the use of modern electronic digital computers to retrieve, compare, and build statistical mathematical models from the input. In the exploration process as part of his broader efforts to evaluate the potential of some prospective region, district, or ore body, the experienced geologist consciously or subconsciously compares and fits the observed geologic features to similar phenomena associated with known ore bodies with which he is acquainted. Thus an adequate conceptual "model" of the total geologic environment and type of ore body sought is an essential requirement for the successful exploration effort. Numerous such models of porphyry coppers already exist in the minds and notes of many experienced geologists today. These models are, of necessity, couched largely in qualitative terms and though they may be quite definite in the mind of the porphyry copper expert, the total concept of what constitutes a porphyry copper deposit and environment is difficult to convey in very precise terms. There probably is no such thing as a typical porphyry copper deposit. However, it is well understood that most of the deposits that have been studied have many geological characteristics in common. A logical question then might be: What characteristics are most common or how often do they occur in common, and what is their relationship to other common characteristics ?

Jan 1, 1970

By K. Fountain

In Novemeber of last year I visited a mica mine in Hunan Province, China. For nine months , we had been trying to sell Chinese mica to a customer in Belgium. Talking to the customer was like negotitating with a stone wall. The buyer refused to communicate any -thing other than his steadfast refusal to consider Chinese mica. He would not advise us what he wanted, what specifications or grades. He would give no indication if our price at market, or reasonable, or totally out to lunch. He would not even accept samples. It took no genius to guess that the mica buyer had at some time in the past bought a shipment of Chinese mica and had received a disaster. I invited the mica mine in Hunan in order to see for myself what could be done - without massive investment in equipment and instruments - to upgrade the quality of the mica for export. We had seen this type of customer reaction before. One disgruntled customer who had pur¬chased pigment grade barites direct from China ranted and raved about unreliable and inconsistent quality. It did no good to explain to him that China is a big country, with hundreds of mines scattered throughout many areas, each producing a different product. Our further explanation that Chinese export organizations also varied in degree and efficiency of customer service fell on deaf ears. Samples had no effect on his perception. Eventually we showed him photoraphs of two mountains of pigment grade barites. One lot was our sales of pigment barites to a major European minerals processor. Our Chinese barites stood proudly white and beautiful next to a hill of other material which now appeared at best mediocre and dull by comparison, and which the buyer had decided to reject after he received our Chinese barites. Finally the customer was sufficiently impressed to look seriously at our guaranteed specification and the outturn analysis performed by our other customer.

Jan 1, 1987

By B. K. Cantrell

The U.S. Bureau of Mines and others have conducted a number of occupational exposure surveys since the publication of the International Agency for Research on Cancer report of 1989, which labeled diesel exhaust as a probable human carcinogen. These surveys have assessed diesel exhaust exposure using measurement of diesel aerosol and/or specific polycyclic aromatic hydrocarbons as indicators of exposure. This paper reviews present diesel emission standards, available diesel exhaust aerosol measurement techniques, and the results of the occupational exposure surveys. In the surveys, diesel aerosol was emphasized because it is a major component of diesel exhaust, is suspected to contribute to the health hazard, and is readily measurable. Three primary aerosol measurement techniques were used: respirable combustible dust, size-selective sampling, and measurement of the elemental carbon fraction. Occupations surveyed included mine workers, railroad workers, forklift operators, fire fighters and truck drivers. The studies found mean diesel aerosol concentration levels in the range of 0.004 to 1.74 mg/m3? Highest aerosol exposures were in confined spaces such as mines where heavy diesel equipment is used. Polycyclic aromatic hydrocarbons typically are found at very low concentration levels and are not unique to diesel exhaust.

Jan 1, 1996

By E. G. Kelly

This paper describes the performance of a modern compound trough profile spiral that is optimized for fine coal cleaning. Reduced performance (Tromp) curves are presented to compare these new spirals with older designs, as well as with other commonly used coal cleaning equipment. As an aid to equipment selection and circuit design, data are also presented to show how variables, such as flow rate, pulp density, and particle size affect efficiency and the separation specific gravity.

Jan 1, 1984

By Grant A. Brackebusch

Paste tailings disposal was successfully implemented at the New Jersey mill in Kellogg, ID with two different types of ore feed, a gold ore and a silver ore. The purpose of this paper is to describe the production of paste tailings, including operational problems during commissioning, and also highlight the environmental and economic benefits that were realized versus conventional tailings disposal such as the recycling of process water, increased shear strength and reduced permeability of the tailings mass, and reduced environmental permitting.

By Elimame Elaloui, Kais Elghniji, Constantin Virlan, Aurel Pui, Chaima Ouled Amor

Separation and identification of minerals composing the Tunisian silica sands have been conducted by acid etching and hot filtration/sedimentation (HFS) without affecting the quartz component. It was found that the hot acid etching process is an effective method to separate quartz and clay minerals in the silica sand. The SEM micrographs of the silica sand show rough surface and some cracks with irregular shapes. The surface becomes clean and smooth after acid etching process. After chemical dissolution, the clay minerals were recovered by hot filtration following by sedimentation at low temperature. FT-IR, EDS maps, and secondary electron (SE) analyses of separated clay minerals reveal the presence of Fe2O3, montmorillonite, and kaolinite minerals. The LIBS analysis of clay minerals shows the presence of Al, Fe, Ca, Al, and Mg. The sequential etching process can be introduced in the purification methods as an effective way to separate quartz from clay minerals.

Jul 29, 2020

"Mining used to be a business primarily focused on the technical aspects of getting valuable ore out of the ground and extracting the minerals efficiently. Without denying the importance of these skills, a narrow focus on technical issues is no longer enough to guarantee success when it comes to exploiting rare earth element (REE) deposits. Molycorp failed to enter the global REE market in a successful manner, while none of the many REE exploration projects has turned into an active mine so far and none is expected to commence operations in the near future. Accordingly, the world of REE is far more complex compared to other commodities. This paper looks into the REE industry to identify the factors that can connect potential U.S. REE mines to the market. The ability to break free from past thinking and become future-focused is a key driver. Mining of REE is pointless without a corresponding value-adding chain, while developing a value chain without first establishing an uninterruptible source of REE is also senseless. The mining sector must be based on the REE value chain and vice versa, along with the establishment of a market channel for the REE products that come out of the mine. INTRODUCTION It has been seven years since rare earth elements became the subjects of front-page headlines. It was when the controversial Chinese export policy for these critical commodities was epitomised in a maritime border dispute with Japan in September 2010 that resulted in the big REE crisis and price spike of 2011 (Barakos et al, 2016c; Mancheri, 2015). The world was dismayed, especially in REE-importing countries, such as the United States that was and is still totally dependent on Chinese production and exports (Barakos et al, 2016c; Kennedy, 2015). The short-lived alarm initiated a treasure hunt by way of exploration for REE deposits all over the world. The continuously growing demand on the one hand and the Chinese sovereignty of the REE-market on the other, led the rest of the world to explore their own REE resources. In just a few years, more than 400 projects were initiated to explore REE deposits outside of China (ERECON, 2015; Goodenough, 2016). The prices of REE, however, dropped rapidly and at the moment of writing this paper are in 6-year lows, at the level of the price average before the 2011 crisis (Barakos, 2017). The viability of even major established producers is being challenged, not to mention the development prospects of potential REE-market entrants (Barakos et al, 2016b; Rollat et al, 2016). Production cutbacks and industry consolidation in China impel REE market experts to forecast that prices have already reached their lowest point and have nowhere to go but up (Adamas, 2015; Roskill 2015). Yet, expectations for increased REE prices are limited and drastic changes are unlikely to happen in the near future, as there is still excess supply in the overall REE market (Barakos, 2017). Nevertheless, the low prices of rare earths are not the only reason that potential producers are struggling to enter the global REE market. Among other parameters, the separation of the individual elements seems to be the most important factor, as it is technically challenging and expensive to build and to operate."

Jan 1, 2018

By Gordon C. ‘Bud’ Presley

The pumice and pumicite review arrived too late for the June issue. Estimated domestic production of pumice and pumicite in 1992 was up compared with 1991, according to US Bureau of Mines statistics. The Bureau estimate of domestic production of 400 kt (440,000 st) for 1991 turned out to be 401 kt (442,000 st) of actual production, the lowest since 1989. In 1992, the estimated the value of pumice and pumicite sold or used in the United States was $11.6 million, up only $200,000 from the 1991 value. There was an increase in the mine, or mill, average price from the five-year low of $11.44/t ($10.37/st) in 1986 to $26.42/t ($23.96/st) in 1992. Estimated tonnage produced in 1992 was 439 kt (484,000 st). Apparent domestic consumption was 642 kt (707,000 st), up 135 kt (149,000 st) from 1991. Imports for consumption were estimated to be 215 kt (237,000 st) last year. Domestic production supplied 68% of the demand in 1992, with net imports supplying the remaining 32%. This compares with domestic production sup¬plying 53% and net imports supplying 47% of the apparent consumption in 1988. Exports were about 900 t/a (1000 stpy) for the period 1984 to 1988. In 1989, exports rose sevenfold to 7 kt (7700 st) and to 20 kt (22,000 st) in 1990. The Bureau of Mines reported that the amount of pumice and pumicite exported in 1992 was 12 kt (13,200 st). It is assumed that these exports were from the Pacific Coast because imports, mainly from Greece, continued to be a market factor on the East Coast and the Gulf Coast States in the United States.

Jan 1, 1993

By Elgin D. Bell

Within the next, year or two, Western Canada should overtake Mexico and France. to become the worlds second largest producer of elemental sulphur, surpassed only by the United States, By 1965, it should produce about 25% of the world's total elemental production and, about 10% of sulphur produced in all forms. In 1952 Alberta had but one small sulphur recovery plant. By 1962, it had fifteen plants with a total designed capacity of almost 6,000 long tons of sulphur per day and actual production of almost one million long tons per year. This decade of dynamic growth was the result of Alberta's rapidly developing natural gas industry. More particularly it was the result of approval in 1960 to export natural gas in large volumes into the United States. Prior approval to export gas from Alberta to eastern Canada and relatively modest volumes to the U. S. had resulted in the construction of several plants but none were of the scale required to serve the U. S. market.

Jan 1, 1963

By John Turner, David Carey

The Robbins Mobile Miner demonstrates the successful combination of hard rock excavation technology and the latest electronic control technology. The mobile miner, a partial face hard rock tunneling machine, features a fully integrated control system relying on a Programmable Logic Controller (PLC). This PLC controls all functions: tramming, steering, boom swing, cutting depth, conveyor operation, air scrubbers, hopper loading and unloading, etc. The machine is fully instrumented allowing the PLC to monitor the results of all commands on a continuous basis, to record data, to evaluate developing problems, or to shut the machine down if necessary. The paper describes the development of the Robbins - Pasminco automated mobile miner and early testing at Pasminco Mining's Broken Hill Southern Operations, New South Wales, Australia.

Jan 1, 1993

By R. Mattos, E. Calcina, G. Quispe, S. S. Kanchibotla

During blasting, rock breaks and moves but standard grade control practices do not adjust ore waste boundaries to cater for blast movement. Rock movement resulting from blasts can result in mischaracterization of grade boundaries resulting in ore loss and dilution. Ore loss takes place when ore is mischaracterized as waste and sent to waste dumps, and dilution occurs when waste is mischaracterized as ore and sent for processing. Las Bambas operations of MMG Peru, realized the economic impact of blast movement on ore loss and dilution and adjust ore boundaries using limited blast movement measurements. This is a step in the right direction but has limitations for everyday application. This paper discusses the advantages of disadvantages of current blast monitoring techniques and introduces an operational tool to estimate polygon movements for different blast designs and confinement conditions. Blast movement estimates from this new tool have been compared against the estimates from the current tools for several production blasts and the results were quite promising.

Mar 2, 2022

By Bernd Hagenah, Katie Theis, Cristina Lauzon, Petr Pospisil

Lidding over or tunneling existing transportation infrastructure is currently under review in several U.S. cities. The main reasons for this are the use of the created space for urban development, the reduction of noise and exhaust fumes for the residents, and, thus, a significant increase in the quality of life. The main aspects to be considered during the planning process are (1) total investment and operational costs, (2) impact of construction works on current traffic, (3) safety and fire protection, and (4) socio-environmental issues. The paper presents some basic planning principles, and experiences of recent urban highway coverages are shared.

Jun 23, 2024

By William Gleason

"While the American Exploration & Mining Association (AEMA) was preparing to close one chapter and begin another during its annual conference in Spokane, WA Dec. 3-7, word of a significant victory on an issue that has been important to the association for many years came from the halls of Washington, D.C.During a keynote address on Dec. 6, Joe Balash, assistant secretary of Land and Minerals Management for the U.S. Department of the Interior (DOI), told a sold-out lunch crowd that the DOI had released final drafts of proposed revisions to the Obama-era greater sage grouse conservation plans. The revisions suggest removing hundreds of thousands of acres of federally protected habitat in Utah, and easing restrictions on energy development and other activities, including mining, in Colorado, Idaho and Wyoming.The protections of the sage grouse were put in place by the Obama administration in 2015. The sage grouse, a prairie fowl, is considered by conservationists to be a key indicator species for the health of America’s sagebrush ecosystem. The previous plan to protect the ground-dwelling bird imposed restrictions to development in sage grouse habitat, but did not place the birds on the endangered species list — a move that many believed would have imposed far more rigid rules.AEMA, and its executive director Laura Skaer, led the way in the fight against the Obama-era greater sage grouse plan, arguing that the plan unnecessarily hurt economic development.“We were the first organization to point out that the greater sage grouse was being used to stop mining, oil and gas production and grazing on public lands in the interior mountain west,” said Skaer who is retiring from AEMA with a significant legal win on this front. “Early on, we cautioned that the proposed Land Use Plan Amendments would be worse than a listing (of the sage grouse) under the Endangered Species Act. Very few believed us until they saw the plans with all of the restrictions and the recommendation for a 4-million-ha (10-million-acre) withdrawal from mineral entry. We were the only organization that filed comments on all 88 Land Use Plan Amendments in 11 states covering more than 24.2 million ha (60 million acres).”"

Feb 1, 2019

By P. Karimi, A. Akcil, A. Amini, H. Abdollahi

"In this study, cyanidation experiments were carried out on a massive sulfide ore sample, whose grades of the precious metals gold and silver were found to be 4.2 g/t and 311.9 g/t, respectively. Other elements in the ore were arsenic with average grade of 1,751.6 g/t; antimony, 619.7 g/t; zinc, 781.4 g/t; copper, 454.6 g/t; lead, 101.8 g/t; mercury, 324.3 g/t; and bismuth, 0.6 g/t. The first objective of test work focused on determining the best conditions for extracting gold from the ore, ground to less than 75 microns. Different influential parameters such as particle size fraction, cyanide concentration, pH and leaching time were investigated. The optimum parameters were found to be particle size fraction of less than 25 microns, cyanide concentration of 2,000 mg/L, pH of 11 and cyanidation time of 24 hours. In these optimum conditions, the highest gold and silver leaching efficiencies were 76.88 and 59.63 percent, respectively. In addition, roasting as pretreatment at a temperature of 700°C over a period of two hours was evaluated. Cyanidation testing of the roasted ore in the optimum conditions found increases in the gold and silver leaching efficiencies to 85.97 and 67.57 percent, respectively. Moreover, antimony extraction rose to 43.10 percent, from 23.73 percent without roasting.IntroductionGenerally, gold ores can be classified as “free milling” or “refractory,” depending on how they respond to cyanide leaching (La Brooy et al., 1994; Celep et al., 2009). While high gold recoveries (> 90 percent) from free-milling gold ores can be readily achieved, refractory gold ores are often characterized by low gold recoveries (50-80 percent) within a conventional cyanide leaching process (Rubisov et al., 1996; Adams, 2005; Celep et al., 2009). The presence of preg-robber components such as carbonaceous matter, sulfide minerals and aluminosilicate can further decrease gold and silver dissolution rates and recoveries. With the negative effect of the presence of preg-robbers, gold dissolution is considerably diminished in solutions with high cyanide concentration (Tan et al., 2005). In such refractory gold ores, gold particles may sometimes be occluded or included in the sulfide minerals, and pretreatment becomes necessary to break down the mineral structure to liberate gold for subsequent recovery. These ores are usually pretreated with an oxidizing process, after which gold and silver can be recovered by a standard cyanidation process. The main oxidizing processes available for refractory gold ores are roasting (LaBrooy et al., 1994; Angelidis and Kydros, 1995; Li et al., 2009; Karimi et al., 2010; Kyle et al., 2012), biological oxidation (Lawrence and Bruynesteyn, 1983; Komnitsas and Pooley, 1990, 1991; Deng and Liao, 2002; Ciftci and Akcil, 2010, 2013) and pressure oxidation (Mason, 1990; Murthy et al., 1992; Qingcui et al., 2009). In addition, ultra-fine grinding is being used in some plants for the liberation of gold and silver particles that are interlocked in the sulfide or silicate minerals (Celep et al., 2011)"

Jan 1, 2015

By Raymond Sandiford, Kenneth Xu, Taehyun Moon

Tunnel approach structures situated in slow moving earth flows are subjected to significant earth pressures. The authors have developed a system, utilizing collapsible concrete columns, that limits such loading. The system uses an array of collapsible concrete columns in front of the structure to absorb downslope movement and limit-imposed loads. This concept has been modelled using 3D FEM analyses and a rudimental lab test. For implementation, the collapsible columns would be prefabricated in strengths to mimic the soil strength profile. This concept has merit, and analytical results demonstrate that collapsible columns are a viable means to limit loading.

Jun 23, 2024

By L. Valentik

Many attempts have been made during the last forty years to evaluate the performance of gravity separation equipment, that is, the effectiveness with which light and heavy particles are separated. The most comprehensive treatment of the subject was made at the 1st International Conference on Coal Preparation held in Paris (1950) by Cerchar. The methods suggested by the Conference were accepted and very widely used in the last 25 years. This paper discusses an improved method of evaluation in the light of the now accepted standard presentation. The float and sink analysis of the product is presented on a Gaussian distribution curve, resulting in an easier visualization of the inherent difficulties of separation. The ogives of the distribution curve are then plotted, giving a quantitative measure of the deviation from perfect separation as an error distance instead of an error area. Illustrations of the new method are given both for gravel and for coal preparation, but the concept is valid and applicable to other types of minerals which are separated by gravity methods.

Jan 1, 1968

By Madeline Mello, Michael Low, Nick Karlin, Bryce Scofield

The LA Effluent Outfall Tunnel is the first tunnel in the United States to incorporate post- tensioning into the precast segmental lining. Several unique components were integrated to ensure that the post tensioning could be carried out successfully in the tunnel, even concurrently with the TBM excavation. This also required the development of new processes both in the casting facility and in the TBM to ensure that the almost 3,700 rings could be successfully manufactured, threaded, stressed, and grouted. This paper will discuss the material selection, fabrication, and installation of, as well as lessons learned from, this first in country tunnel lining.

Jun 23, 2024

By J. R. Heberger

"“Safety Pays in Mining” web application developed by the U.S. National Institute for Occupational Safety and Health Mining Program, helps mines determine the potential costs associated with mining injuries. This web app groups injuries by type, either by the cause of the injury or by the nature of the injury. When the user selects one of more than 30 common types of mining injuries, the app provides information on the distribution of costs of workers’ compensation claims for that type of injury. Based on other user inputs, the app will estimate the total costs of the selected injuries, including an estimate of additional indirect costs, the estimated impact of total injury costs on mining company profits, and provide some examples of other items, such as services or equipment, on which companies could spend the savings that result from the prevention of injuries. This paper reviews the app by discussing its development, how it is used to show the true costs of mining injuries, and how mines can benefit from using it.IntroductionInjuries on the job cause pain and suffering. They can also profoundly affect profits and daily operations. In addition to paying direct costs or increased premiums for workers’ compensation insurance, a company might need to pay overtime for other workers to fill an injured worker’s job role, cover training costs for a replacement worker or divert administrative resources in the wake of an injury. “Safety Pays in Mining” is a web app that estimates the distribution of these injury costs and assesses the impact that occupational injuries have on a company’s profits.The costs of specific types of occupational injuries in mining are not readily available as mining and insurance companies do not usually share this information. As a consequence, companies only have cost information based on previous experience with their own employees. Therefore, if a mine never experienced a finger amputation for one of its miners, for example, it would not be aware of the possible costs associated with this type of injury. In addition, injury costs are unique in that the cost distribution is so wide that just using the average cost of a specific injury type does not provide adequate information. Some injuries involve immensely high costs, and even though the risk of these high-cost injuries occurring is low, mines need to be aware of the potential impact on their company’s financial health."

Dec 1, 2018