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By R. H. Sergent

The interest in using halogens for extracting precious metals from ores has increased due to changes In ore characteristics, environmental concerns and regulations. The rediscovery of halogen leaching capability has been the topic of these and other writers1-30. Much work has been done on the performance of bromine, chlorine and iodine5-29. Of these, bromine and chlorine look most promising. Iodine is quite expensive and sometimes forms an Insoluble film on a precious metal surface22,23. Little experimental work has been published on the relative performance of bromine versus chlorine. The Pourbaix diagrams for the halide leach system (see Fig. 1-4) Indicates a significant stability advantage for bromine In forming complex ions with gold. This should result In greater extraction of gold under similar leach conditions and Is evaluated In this work. The regeneration of halogen from a spent leech solution is a critical requirement for an environmentally acceptable halogen leach process. Bromide can be oxidized In-situ to bromine ~ adding chlorine or ozone2,31. Bromide like chloride can be oxidized In an electrochemical cell to produce halogen on demand 13,15,17. Bromine clearly offers a number of possible regeneration pathways. This work strives to compare the relative ability of chlorine and bromine to extract gold from partially and fully oxidized ores. A commercially pressure oxidized sample was evaluated under a number of experimental conditions. The autoclave feed ore from the same mill was also evaluated after complete oxidation In a laboratory autoclave.

Jan 1, 1993

By Harvey P. Knudsen

This paper describes the results of a comparative study of the geostatistical ore reserve estimation method over three conventional methods; the polygon method, the inverse of the distance squared (IDS) method, and ELIP which is similar to IDS. Each method was evaluated on its ability to accurately predict individual block grades for one bench of the Pima Nine, located near Tucson, Arizona. Results at the Pima Mine indicate that the geostatistical method is no better nor worse in predicting block grades and total tonnage than the ELIP or IDS methods in contrast, the polygon method is clearly inferior. All of the methods would have given better results if geology had been included in the block model. At already producing mines ELlP or IDS may be good choices since they involve substantially less cost in computer time. For prospective or new properties, the geostatistical model is more attractive, due to its ability to construct confidence limits on the estimates.

Jan 1, 1976

By S. K. Kawatra

In most operating coal-cleaning plants, a significant amount of pyrite is recovered in the froth during flotation of high-sulfur coal. Reducing the pyrite recovery first requires that the primary recovery mechanism should be Identified, as different measures are required for reducing entrainment, locked-particle flotation, or true hydrophobic flotation. In this paper, evidence is presented which suggests that hydrophobic flotation is not an important mechanism for recovery of liberated pyrite from freshly-ground coal when the collector is a neutral oil, and that the bulk of the floated pyrite occurs either as a result of simple entrainment or by mechanical locking with floatable coal particles. Column flotation results are also presented which show that significant sulfur reductions can be achieved by reducing levels of entrainment.

Jan 1, 1992

By Liming Yuan, Wei Tang, RICHARD THOMAS, JOHN SOLES, DAVOOD BAHRAMI

Mine equipment fires remain as one of the most concerning safety issues in the mining industry, and most equipment fires were caused by hot surface ignitions. Detailed experimental investigations were conducted at the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Mining Research Division on hot surface ignition of liquid fuels under ventilation in a mining environment. Three types of metal surface materials (stainless steel, cast iron and carbon steel), three types of liquids (diesel fuel, hydraulic fluid and engine oil) and four air ventilation speeds (0, 0.5, 1.5 and 3 m/s) were used to study the hot surface ignition probability under these conditions. Visual observation and thermocouples attached on the metal surface were used to indicate the hot surface ignition from the measured temperatures. Results show that the type of metal has a noticeable effect on the hot surface ignition, while ventilation speed has a mixed influence on ignition. Different types of liquid fuels also show different ranges of ignition temperatures. Results from this work can be used to help understand equipment mine fires and develop mitigation strategies.

Oct 1, 2022

By Mustafa Akser

Dwindling economic deposits of rutile (TiO2) prompted research on recovering it from secondary sources. One such resource is in Southwestern Turkey feldspar mining rejects that contain 5%-6% TiO2 mostly rutile. Previous studies could only upgrade the TiO2 to 36% TiO2 grade, claiming that the leftover flotation reagents on the surfaces of rutile and host minerals detrimentally affected upgrading of the rutile. As a potential remedy to this concern, a laboratory sample (from an operating feldspar mine in Milas, Turkey) was first caustic scrubbed, then air calcined at 400°C to evaporate the oily reagents. Subsequent physical separation of rutile included wet screening, gravity, magnetic, and electrostatic separation technologies. Such processes indeed improved the grade of the rutile concentrate up to 83 % TiO2 Low recovery of the TiO2 (<20%), was attributed to lack of full liberation of rutile, even at 125x44 micron range; interference with impurity minerals such as sphene and zircon; and simply the process inefficiency in upgrading the fine grains through conventional separation technologies for heavy minerals.

Jan 1, 1999

By A. E. Jack Swanson, Brian P. Micke

INTRODUCTION Nevada Goldfields began underground mining development at the Kingston Project in September, 1986, followed by mill start-up in March, 1987. The first gold pour in April followed three years of preparatory work in establishing a North American operational base for the production of precious metals by Golconda Minerals N.L., an Australian mining firm. GENERAL CORPORATE BACKGROUND The Golconda Group of companies was established in early 1983 in Australia. It began operations by successfully retreating tailings at several old gold mining sites throughout Australia. With the limited reserves available for tailings retreatment, Golconda began to look toward the future by conducting a gold exploration program in Australia. However, the continued high price of gold in Australia had limited the possibilities of acquiring good properties at a reasonable cost and consideration was given to looking outside Australia in addition to Golconda&apos;s domestic exploration activities. North America was favored because of the proven potential for substantial gold deposits, the established infrastructure which would allow for rapid and cost-effective development of new projects and the advantages of similar political and economic climates. In mid-1984, Golconda established an office in California and began an extensive study of over 100 prospects throughout the United States. Two prospects were identified as a result of this study whch showed merit; one was located at Empire, Colorado and the other at Aurora, Nevada. Negotiations were then successfully undertaken to acquire these two properties. Golconda&apos;s U.S. offices were moved to Reno, Nevada in early 1985 to facilitate management of its projects. To operate and manage these projects, a small Canadian company listed on the Vancouver Stock Exchange, Cannon Minerals, was acquired by Golconda and renamed Nevada Goldfields Corporation. The current structure of the company is shown below in Figure 1. A private placement of 2,575,000 shares of common stock at US54.00 per share was arranged by Jacksons Limited of Australia in association with W.I. Carr (U.K.) Limited of London. This placement resulted in US510.3 million being available in May, 1986 for the acquisition and initial development of the Aurora and Empire projects. While the financing was underway, project planning commenced on both the Aurora and Empire projects. The Aurora project was selected as the one to be initially developed because of its relatively advanced stage of development. The

Jan 1, 1987

By James P. Connell

The American Concrete Institute defines "shotcrete" as "mortar or concrete conveyed through a hose and pneumatically projected at high velocity unto a surface." This definition thus includes what is traditionally known as "gunite," which is a pneumatically applied mortar. In mining practice, the term shotcrete is restricted to pneumatically applied concrete, and this differentiation will be used in this paper. In 1914, following the invention of the mortar gun in 1907, the then Chief Engineer of the U.S. Bureau of Mines, George Rice, developed the guntie process for underground test work at the bureau facility at Bruceton, Pennsylvania. After World War I, gunite was used extensively in American mines and was also utilized for underground civil works such as the San Jacinto Tunnel in California. The greatest development was In Europe where, as early as 1911, gunite was successfully used as an overlay for deteriorated tunnel linings. In 1951, the Swiss firm Aliva developed a pneumatic gun capable of handling coarse aggregate, thus making possible the first use of shotcrete at the Maggia hydropower development. Intially, shotcrete was used to reduce manpower requirements for forming; and placing conventional concrete. However, by 1954 Sonderegger was reporting that the structural advantages of shotcrete were derived from its flexibility and from the fact that it could be applied almost immediately niter the opening had been made. The incorporation of wire mesh into the shotcrete led to the New Austrian Tunnel Method, or NATM. The use of shotcrete in American mines has been implemented more recently. This delay seems to be due to previously unsuccessful experiences with gunite as a structural material and to the U.S. reliance on wood or steel supports in main line haulageways. The long experience with the apparently more substantial rigid supports led mine operators to be reluctant to the new and seemingly unrealistic lighter shotcrete support.

Jan 1, 1977

By Qinghua Tian, Zhipeng Xu, Dong Li, Xueyi Guo, Liu Zhu

Tellurium (Te) is an important scattered metal. Known as the vitamin of modern industry, national defense and cutting-edge technology, it is the supporting material for new high-technology materials. Currently, its separation and extraction from Te-bearing materials face problems such as long flowsheets and high reagent consumption, giving rise to an urgent need to develop new methods for its recovery.

By Iga Trisnawati, Fitria Puspita, Himawan Tri Bayu Murti Petrus, Gyan Prameswara, Idi Amin, Andi Nurfaadhilah Ulfah

Laterite ores, rich in essential metals like nickel, iron and cobalt, are a crucial resource for modern technology. However, the extraction of nickel from laterite ores is a complex process due to their intricate mineral compositions and low nickel concentrations. This paper presents the results of a study to understand the leaching behavior of preroasted laterite ore and the impact of roasting on leaching kinetics. The ore was subjected to roasting at 280 and 610 °C for a duration of three hours, followed by leaching in sulfuric acid (H2SO4) under atmospheric conditions. The results show that preroasting the ore at 610 °C significantly improved the recovery of nickel during leaching, with recovery rate of up to 93 percent, and the leaching process of the preroasted ore was primarily controlled by diffusion through the ash layer. The activation energy values were found to be 20.97 kJ/mol for the ore roasted at 280 °C, and 18.97 kJ/mol for the ore roasted at 610°C. These findings suggest that preroasting can enhance the leaching performance of laterite ore, potentially paving the way for more efficient and sustainable nickel extraction processes.

Aug 1, 2024

By J. Morris

Petro-diesel is a common collector for fine coal froth flotation but partitioning of diesel range organics (DROs) in process streams has not been widely studied. Preliminary research suggested that under normal dosing schemes total residual DRO in process waters should be limited to the sub-ppm water-soluble fraction (WSF). Further, polycyclic aromatic hydrocarbons (PAHs) should partition proportionately with DRO. The purpose of this study was to confirm these findings in laboratory flotation tests. Total DRO and specific PAHs were measured in tailings and concentrate streams, and coal recovery and ash rejection were tracked. Results show that concentrate waters consistently had higher DRO than tailing waters, and DRO in both streams generally increased with increasing diesel dosage. DRO again appeared to be limited to the WSF and PAHs tended to partition proportionately with DRO. Results indicate optimal flotation performance should generally coincide with minimal DRO partitioning to process waters. Under typical operating conditions residual DRO should not present an environmental concern; however, conditions should be avoided that allow significant overdosing of diesel.

Feb 23, 2014

By R. Tamir

This paper will describe the benefits of utilizing the decision support system, DSS to support the methodology of structured decision-making in the mining environment. It will outline the layers of the mining related decision making – 1. Creation of “one truth” situational awareness utilizing 2. existing planning, ERP, operational and monitoring agents, a. Expressing plan verse performance across mining phases and functions compared with the actual and trends to evaluate performance. b. Creating alternate courses of action and the implications up and downstream. 3. It will review the current condition were although a multitude of technologies resolve multi variable issues they do not interact in a way that assists decision makers throughout the organization in making high-quality decisions that will push the overall performance envelope. 4. The paper will show the benefits of integrating military methodologies to resolve multi variable complexed issues (operational, financial and other), operating in changing environments in order to meet time sensitive objectives with restricted resources. This is achieved by creating a shared situational awareness thru incorporating information from a multitude of data generating agents, creating COA, selecting the appropriate and turning it into a plan. The paper will discuss the implementation and suggest a path.

Feb 1, 2023

By A. W. Khair

This paper presents a strength formula for the design of coal pillars. The formula is derived from results of laboratory experiments, studying the effects of primary factors influencing the strength of the coal specimens/pillars. Five primary factors, significantly affecting the strength characteristics of the coal specimens/pillars were identified and extensive laboratory investigations were carried out. The five primary factors were namely 1) coefficient of friction between loading platens and coal specimens, 2) elastic properties of the loading platens, 3) coal specimen geometry, 4) coal specimen size, and 5) rate of loading. Four to nine levels of variation for each primary factor on the strength of coal were studied. An empirical formula, implementing the variation of the primary factors affecting the strength of coal specimens/pillars, has been developed. A comparative analysis of the results provided by this and some well known formulae is also presented.

Jan 1, 1994

By Edward J. Karkoska

The film you see is a slow motion view of a typical half million ton taconite blast at one of Erie&apos;s mines. This blast is made up of 220 drill holes and a total of 325 thousand pounds of blasting agent. The second view of the same shot is taken by a remote control hi speed camera located 1500&apos; directly in front of the blast. Shortly you will see some violent camera movement as the air blast shock wave strikes the camera location. As the blasting sequence progresses the rock fly becomes evident, and if you will look closely amidst the clouds of smoke, rock fragments weighing up to 1/2 ton begin to cascade into view. These missles are the chief concern of blast security. The next camera shot at 4000 frames/second vividly describes the primacord firing lines detonating the blast. Travelling at 22,000 ft./sec., this white snake of fire travels to each hole, detonating the blasting agent. Before we get into the matter of blast security, let me locate our operation for those of you not acquainted with Minnesota&apos;s iron ranges and tell you something about our company.

Jan 1, 1969

By Alcides Freitas

The great importance of aggregates as a basic building and maintenance material for both public and private projects makes the identification and availability of this valuable resource imperative for our economic and social well being. This was one of the main reasons that led the California Legislature to enact the Surface Mining and Reclamation Act of 1975 (SMARA). The Act requires the State Geologist to classify mineral areas in the state and the State Mining and Geology Board to designate mineral deposits of regional or statewide significance. What is the "Classification and Designation" process and how is it working?

Jan 1, 1984

By V. D. Smar

The flotation process may be considered an interactive system consisting of many chemical, operational, and equipment variables. Changing anyone of these variables causes an overall system response change. This study examines the effects of simultaneously changing the operating variables of: (1) frother concentration and air flow rate, and (2) frother concentration and collector concentration. It is part of a comprehensive study to look at how changes in several of the major variables may be used to produce interactions which will allow the rougher flotation process to be optimized. Ultimate recovery, flotation rate, concentrate grade and froth quality, are used as the major evaluative criteria.

Jan 1, 1993

By Brian Gettinger, Jared Barber, Richard Weatherly, Shannon Dunne, Jeff Masek, Chuck Wolf, Fazle Rabbi, Jack Canfield

During Hurricane Harvey over 60% of the 39 WWTPs, including the low-lying 25 MGD Sims North WWTP, and one third of the 382 lift stations owned and operated by the City of Houston were flooded resulting in extensive facility damage, loss of service and uncontrolled release of untreated wastewater into bayous and creeks. In response, the City has embarked on an effort to improve system resiliency by consolidating at-risk facilities with a network of deep sewer tunnels. These tunnels will provide secondary benefits to the collection system of augmenting the capacity of the existing 6,000 miles of sewer mains and lowering the collection system profile in poor performing areas. Investigations on the cost to mitigate the flood damages by raising the liquid stream processes at the Sims North WWTP is estimated at nearly $450 million. Instead of spending $450 million to raise the plant, the funds will be directed to providing a more robust and resilient wastewater system for the Sims basin area of Houston. The backbone of this new system is a 4.5-mile-long, 110 inch diameter deep gravity sewer tunnel that will convert a system heavily reliant on distributed lift stations to a majority gravity system with a deep consolidated lift station at the Sims South WWTP. This will also allow the City to address the flood prone infrastructure at Sims North and consolidate its operations into a single permitted outfall for this collection system. This approach is the outcome of a team effort focused on maximizing system resiliency and sustainability for the next 100 years. By thinking outside the box, the City of Houston will not only mitigate the flooding risk at Sims North WWTP, but also solve regulatory and operational challenges throughout the sewershed and deliver a winwin on multiple levels.

Jun 13, 2021

By Ed Schodowski

Wireless technology is a hot topic for anyone involved in the design, operation, maintenance or upgrading of mines or mineral processing plants because wireless technologies overcome barriers that have prevented many useful data inputs. Wireless communications can contribute to worker safety, satisfy environmental concerns, support plant security, track human and physical assets, and improve equipment maintenance. The cost structure of wireless is compelling and users can realize savings ? up to 90 percent less installed cost than wired instruments ? since wireless technology eliminates the need for expenses associated with cabling, engineering, construction and documentation. Many applications previously considered too expensive have become economically feasible with wireless. Two examples are continuous monitoring of safety showers to notify operators when one has been activated, and monitoring effluents to ensure environmental regulations are being met. In many cases, wireless transmitters can be installed where wired devices were too expensive to justify, or were not feasible due to physical or technical barriers. Examples include monitoring temperature measurements inside a rotating reactor or monitoring process variables in a tough, corrosive environment too challenging for a wired solution. Wireless also gives operating personnel mobility with the ability to communicate from remote or hard-to-reach zones. According to a recent Venture Development Corp. survey covering radio frequency (RF) of microwave industrial monitoring and control products, these features are contributing to the expected nationwide growth rate for industrial wireless applications of 19 percent annually from 2007 to 2012 (Taylor, 2008). At the same time, mineral producers have many questions about wireless systems including their applicability, reliability and security in this industry. Just what can wireless do? Is it secure and reliable? Can these instruments stand up to the rigors of the industry? Can wire-less technology provide the flexibility needed for mining applications?

Jan 1, 2009

By Elif Emil-Kaya

Samarium (Sm), as one of the rare earth elements (REEs), has gained significant attention in the production of samarium- cobalt (SmCo) magnets due to their high corrosion and oxidation resistance, as well as their high-temperature stability. SmCo magnets find applications in various industries, including but not limited to national defense, aerospace, military and medical equipment. Sm and Co have been classified as critical metals due to their economic importance and supply risk. Recovering Sm from SmCo magnets is an effective method to ensure a stable supply. The present study investigates an integrated hydrometallurgical treatment and combustion process for the preparation of rare earth oxide (Sm2O3 ) powders from SmCo. Initially, SmCo powders are exposed to nitric acid, and the resulting slurry is selectively oxidized at 250 °C to obtain Sm(NO3)3 , Co2O3 and Fe2O3 . Subsequently, the selectively oxidized powders are leached with water to extract Sm. Sm2O3 powders are produced from the obtained leaching solution using an energy- and time-efficient solution combustion process. Finally, the optimal conditions for the production of Sm2O3 are identified, and the produced powder is characterized through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis.

Nov 1, 2024

By F. P. Jung

This presentation will be a general overview of the Cerrejon Coal Project being developed jointly by Carbocol, an entity of the Colombian government, and Intercor, an Exxon affiliate. The word "Cerrajon", by the way, is simply Spanish for a small hill. There is a distinctive hill near the mine site, and it&apos;s the only landmark of any significance. It&apos;s shown in Figure 1. So the locals call this area "El Cerrejon", "the little hill." Let me start with some of the highlights of the project, summarized in Figure 2, and then go into more detail later. A four-year feasibility study covered the geology, quality, engineering, construction operation and marketing of coal from this region. This study led Exxon to declare the project as commercial in July of 1980. Then in September of 1980 the president of Colombia gave the government&apos;s okay to proceed.

Jan 1, 1982

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. Alternatively, the organic efficiency parameter does consider process economics; however, it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach is introduced which reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure which reflects a better use of performance data. INTRODUCTION Partition curves are commonly used in the characterization, evaluation, and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, and density separators. Graphically, the partition curve depicts the recovery of particles as a function of a physical property on which the separation is based (e.g. particle density, size, magnetic susceptibility, etc.). Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic “S” shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout (or bypass) values, the midpoint slope, and the separation cut point (property value with 50% recovery). Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of the calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, since a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point (i.e. an infinitely large slope). One common formulation of this slope, the Ecart Probable (Ep), is derived by evaluating the slope between the 25% and 75% recovery points:"

Jan 1, 2015