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By M. S. Celik, H. Du, J. D. Miller, F. Cheng, O. Ozdemir

"In this paper, recent progress with respect to the flotation chemistry of soluble salt minerals is reviewed, and some of the more relevant issues including the hydration states of ions, the interfacial phenomena of salt surfaces and the flotation behavior of selected soluble salts are discussed. Due to the high solubility, the flotation of most soluble salts has to be carried out in their saturated brines. Anecdotal evidence has suggested that the hydration states of the ions have significant influence on the physicochemical properties of the solutions, the surface charge and wetting characteristics of the minerals, the collector adsorption states and, further, the flotation behavior of the soluble salts. In this regard, reviewing past research findings, efforts are made to establish a correlation between the ion hydration states with the flotation behavior of the soluble salts. Further, advances in understanding the significance of colloid adsorption involved in the soluble salt flotation process are addressed, and future research efforts to understand the soluble salt flotation chemistry are suggested.IntroductionSoluble salt minerals are essential raw materials for the production of a variety of commodities, fertilizers, potassium hydroxide, soda ash, magnesium compounds and other chemicals. These soluble mineral resources can be processed using flotation technology and, currently, more than 80% percent of the world’s potash is produced by the selective flotation of KCl crystals (sylvite) from other salt crystals, predominately NaCl (halite) and other more complex salts (Searls, 1990). Despite the successful application of flotation technology in the potash industry, the mechanisms for collector adsorption on soluble salts have not yet been fully understood and, therefore, have been of considerable interest to flotation researchers for many decades."

Jan 1, 2015

By Ewan Alexander

"As human beings, we have managed risk since the dawn of the ages and have been adept at doing so. In order to survive, we hunted or gathered. If we did not take enough risk, we died. If we took much risk, we died (Fig. 1). As individuals and tribes, risk had to be optimized to maximize our chances to thrive, as individuals and as tribes.In today’s world, the risks are vastly different, but in order to thrive, these must be managed. And no industry knows this as much as mining. In fact, the International Council of Mining & Metals (ICMM) has proposed the Critical Risk Model (Fig. 2) as a means of identifying critical risk, critical controls and associated performance standards. The ICMM focuses on sustainable development performance in the mining and metals industry. It has 23 members, representing some of the largest mining companies in the world.This approach is going to help the mining industry. But it must be applied effectively, with the acknowledgment that the system alone cannot be effective. We can say this confidently, as even companies known for the strength of their risk and safety management systems continue to experience significant incidents, and, in some cases, catastrophes. Why does that happen when all safety metrics, including injury rate, are pointing in the right direction? In the view of the author, it is only when leadership, culture and systems work in complete harmony that the resilience of an organization to manage its significant risk is at an optimal level. It remains an ongoing leadership challenge to maintain that balance and the optimal mindset in the organization. So how do you maintain that special balance?Let’s start with a basic premise. Leadership, supported by simple effective systems, creates culture which creates outcomes. Everyone going home safely is an outcome, as is cost effective operations, and to achieve those outcomes efficiently, the organization must focus on the inputs. And those inputs include effective leadership, effective systems (for the purposes of this article, risk and health, safety and environment (HSE) systems), good planning, stable operations and competent workers. This article will focus on gaining maximum performance from your risk management system."

Oct 1, 2016

By SUHAINA ISMAIL, NORLIA BAHARUN, SHAIK ABDUL RAHMAN, WAN NUR SYAFIQAH ANUAR, MOHAMMAD REZAEI ARDANI

Refractory gold ore contains sulfide minerals like pyrite, chalcopyrite and sphalerite that are difficult to be directly leached by cyanidation or by lixiviants such as thiourea and halides. In such cases, it is necessary to perform oxidative pretreatment of the ore to oxidize the sulfide matrix, and gold particles can be exposed to the solution during the leaching process [1]. In recent years, hypochlorite and chloride solutions have been introduced as alternative materials for hydrometallurgical methods of gold extraction instead of cyanide solution [2]. A previous study by Hasab et al. [3] reported that the gold dissolution rate in hypochlorite solution was higher than in the cyanidation process, due to the presence of hypochlorous acid (HOCl) as a strong oxidizing agent. In a hypochlorite leaching system, the change in pH can influence the presence of oxidant species in the solution: the hypochlorite ion (OCl−) is stable in pH greater than 7.5, HOCl can be found in pH between 4.0 and 7.5, and aqueous chlorine (Cl2 (aq)) is the predominant oxidant when pH is below 4.0. As HOCl is the most effective oxidizing agent for gold extraction, pH should be maintained in the range of HOCl stability [4].

By MOHAMMAD R. H. GORAKHKI, CHRISTOPHER BAREITHER, MANUEL APARICIO, IV JOSEPH SCALIA

Comingling filtered tailings and waste rock in a tailingsdominated mixture is a mine waste management strategy that has the potential to create geotechnically and geochemically stable landforms. Potentially acid-generating (PAG) waste rock can be sequestered within a filtered tailings matrix to enhance water retention and decrease hydraulic conductivity relative to a waste rock pile, potentially minimizing acid rock drainage (ARD). Enhanced water retention can reduce oxygen ingress limiting oxidation and resultant acid generation. Reduced hydraulic conductivity can slow inward percolation and outward drainage. In dry climates, the tailings matrix can hold precipitation near the ground surface accessible to evaporation and transpiration, thereby decreasing percolation. This paper presents an evaluation of comingled filtered tailings and waste rock in a tailings-dominated mixture (termed GeoWaste herein) and illustrates that ARD can be reduced under field conditions in a subtropical–highland climate.

By Richard L. Bullock

Believe it or not, mine evaluation and feasibility studies are as old as the industry itself. In the first recorded writing on mining by Agricola (1556), he gave several clues as what to look for in evaluating a mine, to determine if it was economically feasible. Below is the guidance from Agricola, with my interpretation of what he would include today. Now a miner, before he begins to mine the orebodies must consider seven things, namely: ? The situation (the geography/topography). ? The conditions (the geologic/mineralogic and mining conditions). ? The water (availability, hydrology and ownership). ? The roads (plus the railroads, power lines, all other infrastructure). ? The climate (the weather-rainfall/environment). ? The right of ownership (the land and legal entitlement). ? The neighbors (the social environmental concerns of the area). It is amazing how much of his guidance has not changed in 455 years. Yet Agricola gives no guidance on determining the correct cost, or determining the correct commodity pricing. But he does give a few words of caution on the related ethics involved on buying mineral properties: ?A prudent owner, before he buys shares, ought to go to the mine and carefully examine the nature of the vein, for it is very important that he should be on his guard lest fraudulent sellers of shares should deceive him.? Three hundred years later (1866), to further amplify this point, in the most famous thing that Mark Twain never said, as an introduction to a lecturer to an audience of gold-miners at Red Dog, CA, the famed author/humorist allegedly described a mine as ?a hole in the ground owned by a liar? (Farrar & Rinehart, 1935). So, one might conclude that between these two dates, the mining industry did little to improve its reputation. Unfortunately, since Mark Twain allegedly made those remarks, we have not done near enough to gain accountability for the mineral industry.

Jan 1, 2011

By A. M. Anthony, A. Y. Atta, S. S. Magaji, U. Abubakar-Zaria

There are two major gold recovery methods: the hydrometallurgical technique, which employs cyanide solutions, and amalgamation method, which involves mercury (Hg). These methods present considerable health, safety, and environmental concerns. Past applications of alpha-cyclodextrin (α-CD) on gold scraps show that α-CD is not only inexpensive, but is also environmentally friendly. This research work used α-CD to recover gold from gold ores instead of gold scraps. The gold ore was sourced from Shanono gold deposit site Kano State,Nigeria. The gold ore was characterized by fire assay (FA) for the precious metal. The concentrate was digested with aqua regia (AR) for 24 h. Modified AR, where hydrochloric acid was replaced with hydrobromic acid, was used for the gold digestion due to the good match in molecular recognition between gold bromide ion (AuBr)− and α- CD in a second sphere coordination complex. The digestate was characterized using atomic absorption spectroscopy (AAS). Gold recovery using this technique is pH sensitive, and five pH values (2.0, 3.6, 4.0, 5.4, and 6.0) were investigated. FA analysis showed the Shanono gold ore deposit contains an average of 4.71 ppm of gold, AAS analysis showed highest gold recovery of 69% at pH 4.0, which is lower than recoveries from the metal scraps. This could be due to the presence of other gangue minerals closely associated with the ore. However, gold recovery using α-CD on Shanono gold ore has shown to have a higher yield of 69% compared to 35.5% yield obtainable by Artisan Small Scale Miners using mercury.

May 5, 2020

By D. D. Eyer

New or improved technology will continue to drive productivity improvements through the next decade. In January 1988, I presented a paper titled, "Large Underground Mines of the 1990s? before the SME. I will follow some of the themes developed in that paper as modified by our experience in the past two years. In order for a coal company to be profitable today, it has had to reduce unit costs experienced in the past. This is because the current average realization, even accounting for a recent strengthening, remains below that of a few years ago. Doing business as was done in the past is not good enough. The coal industry needs to increase productivity in the range of 5-10% annually merely to stay even with rising costs. Underground productivity has been increasing more rapidly than that for surface mining. With the exception of the Powder River basin of Montana and Wyoming, underground productivity has caught up with that for surface mining in many regions of America. There are a number of technological factors which have attributed to increases in underground productivity and which should be factors in the future.

Jan 1, 1990

By F. Carew

Accurate knowledge of what mass and grade is to hand and where it is stored is key to mine efficiencies and overall profitability. In order to make the right decisions and align production with stockpile capacity, feed and contract demand, a clear and accurate view from production through blending and processing is required. The use of a mine production management solution can provide you with a high degree of confidence in and visibility into validated data as well as auditable and traceable material movements, activities and surveys. A robust calculation engine enables mass and grade changes to propagate to material movements and stockpiles to ensure you are getting the most accurate view at all times. Tracked changes in material balances can be readily incorporated in revised production schedules to close the loop. The availability of accurate, timely information, coupled with predictive trend indicators, is a significant advance in narrowing the gap between claimed and planned production that is common to many mines, regardless of commodity. This paper provides an overview of a Mine Production Management System (MPMS) and explains how the system helps address the challenges listed above.

Jan 1, 2011

By H. W. Breathitt

World demand for phosphate rock has increased significantly in the past fifteen years. Prior to the early 1960's, most of the world production was obtained from Florida, North Africa, and Kola. As the 1960's arrived, new mines in North Florida and Eastern North Carolina, as well as expanded production in the Western United States, .increased domestic production. Many new mines overseas have also become significant. This includes countries such as Senegal, Togo, Israel, Spanish Sahara, and Jordan. Limited production, often as by-products, has been noted in South Africa, Brazil, and other countries. In recent years, and even recent months, we have learned of many new areas being considered as potential sources of phosphate rock. This includes Australia, Saudi Arabia, Mexico, Colombia, and Brazil. Many other developing countries have discoveries and are considering their new deposits, often with difficult beneficiation problems, as potential sources of phosphate. These factors all relate to expanded world, population and the demand for more fertilizer products to produce food. In this paper, four areas of the world with different types of phosphate deposits are briefly reviewed to contrast the ore beneficiation problems to Florida procedures--long considered the "standard" of the industry, at least for most of the United States' domestic production. Agrico has three large operating mines in Florida with total production capacity exceeding seven million tons per year. Here, pebble phosphate (+14 mesh material) is produced without the use of flotation, whereas all of the material finer than 14 mesh is subjected to flotation beneficiation to upgrade into high grade concentrates.

Jan 1, 1977

By S. Hamm

Elevated total dissolved solids (TDS) content in waters downstream from surface coal mines in Central Appalachia is an increasing concern, as unnaturally high TDS and/or associated specific conductivity (SC) may contribute to deteriorated stream ecosystem health. The aim of this preliminary study was to explore the efficacy of accelerated leaching as a means of minimizing long-term TDS/SC generation by problematic overburden materials. Five spoil samples were collected and leached using simulated rainwater solutions under ambient and acidified pH conditions. SC and pH were monitored during each leach cycle, and ICP-MS was used to determine how leaching conditions affected release of specific ions. This paper highlights the results of both jar and column leaching tests. Among the most significant findings was that, for certain spoil materials, SC in leach column effluent was effectively reduced when spoil was leached first with acidic rainwater followed by ambient rainwater (vs. ambient rainwater leaching alone). This suggests that accelerated leaching might aid in long-term stabilization of some materials.

Feb 23, 2014

By Donald D. Murphy

My first contact with underground, bolt conveyors came when I was hired as a draftsman by the La-Del Conveyor & Manufacturing Company in 1935. At that tine relatively few nines were using haulage belt conveyors. Wore they were in use, they were usually loaded by chain or shaker type room conveyors which in turn were hand loaded at the working face. Duo to the low room tonnage, a gathering belt might receive who output of from six to eight rooms. For several years belts 26 and 30" in width were the favorites for coal mine use. Belt speeds very seldom exceeded 200 ft. per mm. at that time. Conveyor lengths for the majority of units lay between 1.000 and 2000 ft. For a number of years 25 H.P. drives were adequate for those conveyors. From 1940 until about 1950 loads and speeds went up slightly and 40 H.P. drives became the standard. Since the majority of mines were then using direct current power systems, we were able to use controllers with 3 or more steps of starting resistance. The slow belt speeds coupled with relatively long starting cycles kept the rate of acceleration low and gave us smooth, easy starts.

Jan 1, 1963

By Yunxing Cao, Xinsheng Zhang, Bingbing Meng, Shuaifang Guo, Li Wang, Junsheng Zhang

During the initial process of mining a longwall working face, it is often found that the roof will not collapse readily, which increases the risk of later roof collapse disasters. Explosive and hydraulic fracturing are common roof weakening techniques; however, they have certain limitations. In the present study, CO2 fracturing was used for roof weakening during the initial mining phase in the Changcun coal mine, China, which is a novel strategy. First, by analyzing the lithological characteristics of the working face and applying combined beam theory, the breaking spans of the top coal, immediate roof, and main roof were determined before weakening. An F-35 CO2 fracturing device with a rated pressure of 270 MPa was used, which provides fracturing energy equivalent to 0.968 kg of TNT. The fracture radius of the main roof was studied by ANSYS/ LS-DYNA combined with the hanging roof-breaking theory to determine the optimal layout of CO2 fracturing drills. The results show that the breaking spans of the top coal, immediate roof, and main roof were reduced by 3.99 m, 7.66 m, and 22.03 m, respectively. The main roof collapsed as the working face advanced, eliminating the chance of later roof collapse disasters. Compared with hydraulic fracturing and explosives, CO2 fracturing is safer and more practical, giving it significant application potential.

Nov 23, 2023

By Serdar Aktaş, Burcu Nilgün Çetiner

According to critical statistical studies, antimony is one of the rarest elements in the world, and global resources could be exhausted by 2050. In light of these observations, its extraction will be costly due to poor-quality ore, deep mining, remote locations, and high energy consumption. In the present study, an alkaline leaching process was carried out on stibnite concentrate to evaluate the effect of reaction parameters on the percentage of antimony extraction. The leaching efficiencies of different sulfur and hydroxide sources were studied and compared to one another to create a better understanding of the reaction process. Kinetic models were investigated to identify the reaction pathway and calculate the activation energy. The activation energy of the stibnite dissolution was assessed as 19.13 kJ/mol using a two-dimensional diffusion-reaction model. The value of activation energy indicates the quantity of energy necessary for a reaction to proceed. As expected, potassium hydroxide leaching was significantly more successful than was sodium hydroxide; however, in terms of economics, the use of sodium hydroxide was found to be more cost-efficient. Interestingly, this finding indicated that caustic leaching is still the most effective method for stibnite extraction.

Jul 23, 2020

By Todd Minoski, KRISTIN FLOYD, Michael Murphy, VASU GANGRADE, Gamal Rashed, DYKE MARK VAN, Brent Slaker

Underground stone mines frequently operate on multiple mining horizons or are required to undermine or overmine old workings. In these situations, the effects of pillar columnization and interburden thickness on the stresses surrounding mine workings are poorly understood. Many old workings were not designed to consider the effect on future undermining or overmining and, as a result, are laid out on irregular patterns and with pillar sizes that are difficult or impossible to replicate on adjacent levels. Additionally, as depth increases, even a consistent gridded mine layout may result in poor columnization due to the need to increase pillar sizes. Rules of thumb and past practice for designing multiple levels may often be effective. This paper explores the effect that multiple-level stone mining has on stress redistribution through the discussion of two case-study mines and associated numerical modeling to provide additional insight into situations which may cause concern.

By Harvey W. Parker

Our industry has developed to the skilled, experienced and productive industry that we now enjoy as a result of the visions of great engineers throughout history, but, in particular for their visions in the last 1 centuries. Unfortunately for our forefathers, the technology lagged so far behind that these exceptional visions could not be realized for decades, sometimes for a century. All that has changed in recent time and many bold and visionary projects can now be constructed and operated because of dramatic advances in technology. Before, say, 1950, tunnel technology developed very slowly. However, technology is now developing at such a fast rate that planners and decision makers are challenged to stay ahead. Moreover, new technology will develop during the lifetime of any project that can dramatically improve under-ground space projects. One of the best examples of this technological advancement is that of closed-face TBMs which now make tunneling feasible in previously impossible ground conditions. Since it usually takes a decade or more to plan, overcome environmental and political issues, construct, and put into service major projects, planners and designers are challenged by the changes in technology that occurs during the long time span of planning and construction. This is particularly true of large infrastructure projects such as transportation, water and wastewater systems and other major underground schemes. Also, since the serviceable life of many of these tunnels is often over one century, planners must consider not only lessons learned from the past but also what new concepts and innovations may develop over an extremely long time. These and other issues create a great challenge to planners and illustrate the great importance of careful but creative vision and flexibility during planning of long-term tunnel and underground space projects.

Jan 1, 2008

By C. V. Baltzer, E. L. J. Bingham

Compliance with the EPA's emerging Clean Water Act regulations can be challenging. Open pit copper mines in Arizona have found themselves in a tangled web of changing rules, regulations, and guidance documents regarding storm water and process water discharges. Large mining properties must come up to speed on a myriad of issues including the definition of zero discharge, what constitutes a process related spring or seep, and tailings and waste rock Best Management Practices. The example of the Pinto Valley Mine in Arizona is used to illustrate National Pollution Discharge Elimination System regulatory issues.

Jan 1, 2001

By Setareh Afrouz, Emily Sarver, Cigdem Keles

The resurgence of severe lung disease among US coal miners since the mid-1990s has led to efforts to better characterize and monitor respirable dust exposures, particularly focusing on mineral constituents from rock strata surrounding the coal. A rapid analysis method for silica (quartz) mass using direct-on-filter Fourier transform infrared (FTIR) spectroscopy has been developed, which can also estimate kaolinite, a primary silicate mineral in many coal mines.

Feb 24, 2022

By Eugene N. Cameron, Igor N. Sviatoslavsky, Harrison H. Schmitt, Gerald L. Kulcinski

The recent discovery of large amounts of helium-3, a valuable thermonuclear fuel, on the surface of the Moon has prompted engineers and scientists to examine the commercial attractiveness, thetechnological feasibility, and the environmental features of this important resource. The main feature of this fuel cycle is the low (˜ 1%) fraction of energy released in neutrons. Such low neutron fluxes result in important reductions in the amount of radioactivity, afterheat, and radiation damage in a fusion power plant. On the other hand, the high fraction of energy in charged particles and synchrotron radiation can be directly converted to electricity, resulting in very high efficiencies of electricity production (˜60.70%). It has been shown that there is 10 times more energy in He3 on the Moon than there ever was in fossil fuels (i.e., coal, oil, and gas) on the Earth. The techniques and equipment needed to extract the helium-3 have been examined and internationally acceptable mechanisms for the industrial development of this resource have been outlined. This paper expands on the financial, environmental, and technical aspects of the recovery of helium-3 for use in the 21st century.

Jan 1, 1990

By QUANWEN PU, Yonggang Wei, Bo Li

The spent catalyst is one of solid waste resources, which contains precious metals with considerable recovery value. However, due to the different compositions of catalyst, the recovery process is difficult. Most of the catalysts are supported by alumina which has good alkali-soluble properties, while platinum is insoluble in alkali. Platinum is enriched by pressurized alkaline solution which is a kind of hydrometallurgical process. The novelty of this study is the separation of alumina and platinum from the spent catalyst and the enrichment of platinum in the solid phase. In this study, a leaching process using NaOH as leaching agent under high temperature and pressure was employed. The effects of alkali concentration, leaching temperature, leaching time, and liquid–solid ratio on leaching efficiency were investigated. The optimum process conditions were determined as follows: alkali concentration of 240 g/L, temperature of 200℃, pressure of 1.20 MPa, time of 1 h, liquid–solid ratio of 5:1. It was concluded that the leaching rate of alumina can reach 99.69%. The content of platinum increased from 0.1749 to 21.12%, the loss of platinum was 3.39%, and the enrichment ratio of platinum increased by 120.82 times. The leaching kinetics of alumina was studied based on the shrinkage core model. The activation energy of alumina leaching is 19.53 kJ/mol, and the leaching process is controlled by chemical reaction. Pressurized alkali solution can not only efficiently leachate alumina from the spent catalyst and enrich platinum, but also reduce the reaction time and increase reaction rate.

Feb 11, 2022

By F. Milton Lewis

In this paper an attempt has been made to review the cost trends in producing copper by conventional milling. smelting and hydro-metallurgical means during the last five years. The primary objectives of this cost analysis are to provide a base for future projections as well as to indicate which cost items are more volatile in their influence on overall cost of producing copper.

Jan 1, 1977