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The National Institute for Occupational Safety and Health (NIOSH) conducted field tests to evaluate the effectiveness of a wet head continuous mining machine for reducing dust exposure for continuous miner operators. Wet head technology delivers water via sprays to the continuous miner's cutter head as opposed to traditional standard sprays located on the boom and body of the mining machine. The sprays, positioned directly behind each bit on the cutter head, deliver water at the point of attack, serving to cool the bits during mining to reduce the potential for frictional ignitions. The sprays also flood the coal with water to potentially suppress dust generation. Dust surveys were conducted at several mines to evaluate the wet head's effectiveness to control respirable dust exposure at the continuous miner operator location and in the immediate return. Results show that the wet head miner improved air quality at both locations to varying degrees in some cases and not in others when compared to a continuous miner with a standard spray system.

Jan 1, 2010

By R. H. Church

The Bureau of Mines' Tuscaloosa Research Center has developed a field test unit (FTU) which dewaters mine and/or mineral processing by-product slurries. The feed material (by-product slurry) is mixed with a known quantity and specific type of synthetic polymer (usually a polyacrylamide) to induce flocculation in a continuous operation. The flocculated material passes over a specific number and size of slotted stationary screens which separates the flocculated solid material from the "clean" water. The "static screens" are positioned at a fixed angle to maximize flow capacity and capture of the solids content. An investigation was conducted at an industrial crushed stone operation located near Birmingham, AL, to determine if the Bureau's FTU could successfully dewater the waste slurry generated during grinding and sizing operations at this facility. The investigation showed that waste slurries could be dewatered to 50 pct solids, at a polymer cost of approximately $0.85/ton of dry solids treated, and resulted in approximately 85 to 95 pct solids recovery. The dewatered material continued to consolidate and reached 69 pct solids in 24 h. Presently, the waste slurry generated at this facility is discarded into impoundments. However, this research has identified the recovered waste as an economically marketable product.

Jan 1, 1994

By J. Driscoll

After 30 years of success, Newmont Gold Company has temporarily ceased production from the original Carlin Pit. In late 1993, the Carlin East Decline was driven and an extensive underground exploration program was started. Today, Newmont Gold produces refractory ore from the Carlin East underground at the rate of 700 t/d (770 stpd) for an annual production of over 100,000 ounces. Over 70 underground miners enjoy the estimated 6-year mine life at Carlin East. About 70% of the ore at Carlin East is mined by mechanized longhole stoping with delayed cemented backfill. The remaining ore is mined by underhand drift and cemented fill methods.

Jan 1, 1997

By M. M. Botz

Cyanidation tailings which are disposed in a surface impoundment experience a loss of cyanide due to natural degradation, frequently reducing the cyanide concentration to very low levels. Quantifying cyanide losses in terms of pond geometry, local weather conditions and feed solution chemistry has been largely empirical though in many cases mining operations rely on surface impoundments to reduce cyanide to below an internally regulated concentration or an effluent limitation. To permit a more quantitative evaluation of cyanide losses in an impoundment, a computer simulation was developed to estimate the losses of free, WAD and total cyanide due to dissociation, photolysis and volatilization. Results of the model are compared against data collected for a North American tailings impoundment during 1998.

Jan 1, 1999

By J. Kretschmann, T. Rudolph, L. Michael, P. Goerke-Mallet

The mining value chain plays an important role in our societal development. Even in a circular economy, mining and raw materials are in great demand, and so are skilled engineers. In Germany, many students decide to pursue STEM studies in the tertiary degree. Nevertheless, the OECD reports low completion rates in obtaining the degree of studies [1]. Generally, the dropout rates in STEM education are high [2]. Many students have difficulties with basic subjects such as science and mathematics, in which they lack knowledge they should have acquired in school [2]. With the German STE(A)M project PepperMINT (https://peppermint.thga.de/), the Technische Hochschule Georg Agricola (THGA) offers a digital and open educational platform, as a dynamic, massive open, online course (MOOC) for students and prospective engineers. The project is funded by the RAG-Stiftung (RAG-Foundation; No. 20-0004). Using adaptable MOOC classes and applied examples from the wide-ranging cycle of mining activities, we motivate students to engage in STEM studies. Our adaptive and application-oriented content demonstrates the diversity of jobs and career paths in the mining industry. The integrations of applied examples and research activities of the Technische Hochschule Georg Agricola can increase the curiosity and motivation of learners. In mathematics, mine-surveiying technologies and geomonitoring methods (see figure 1) can be used to teach trigonometry. Additionally the concept of the free open online classes enables students in high school to get insights into the field of engineering before they decide the subject of their studies. For freshmen who already decided to pursue a STEM degree, the PepperMINT courses can help to identify and close knowledge gaps and to align different levels of knowledge within a heterogeneous student body. Empowering students in STEM education and integrating examples from mining research can help us train the mining engineers of the future.

Mar 2, 2022

By Jaime Lomelin

The brines from the sub-surface of the Laguna del Rey dry lake are pumped to Química del Rey, S. A. plant, where they are cooled in adiabatic crystallizers precipitating sodium sulphate decahydrate. This salt is dehydrated in multiple effect evaporators and dried in rotary kilns producing high purity anhydrous sodium sulphate. The spent brines from the sodium sulphate operation are concentrated in solar ponds, precipitating astrakanite and leaving a brine with a higher concentration of magnesium ions. This brine is treated with calcium chloride solution to eliminate the remainder of sulphates, leaving a solution of magnesium chloride ready for the manufacture of refractory grade magnesium oxide or periclase. The magnesium chloride is reacted with dolime to produce magnesium hidroxide which is washed, filtered, and calcined to produce soft burned magnesium oxide, which is briquetted and dead burned to produce the periclase.

Jan 1, 1984

By Henry N. McCarl

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Jan 1, 1966

By Daniel T. Brian, O&apos

Exploration targets and results in the mining industry are commonly summarized in terms of tonnage and grade. Business appraisals require, as additional information, the expected profit or loss implied by the physical summary. The early incorporation of knowledge gained through financial analysis computations can provide a means for economically resolving many common exploration and development problems. Examples of such applications from the activities of exploration planning, reconnaissance, land acquisition, and development planning are presented in this paper.

Jan 1, 1969

By Y. S. Roditis

Traditionally, open pit optimization has been used to produce a single outline which can guide the pit design. This paper describes how a series of optimum nested pits are utilized to: a. produce different mining sequences and to help in mine planning and phase design; b. evaluate different metallurgical processes, production scenarios and equipment size; c. investigate the sensitivity of a project to prices, recoveries, production rates, costs, ultimate pit slopes etc.

Jan 1, 1993

By Robert J. Pruett

The Georgia kaolin District is the world's largest producer of kaolin. Georgia production tripled from 2,344 million metric tons in 1964 to 7,570 million metric tons in 1994. Development of the Georgia kaolin industry can be traced to the mineral resource, the adoption of innovative process technologies, and the market growth for kaolin. Georgia kaolin is an abundant and high-quality resource that shows a range of advantageous properties. Technical developments in wet processing, delamination, and calcination allowed production of high-value products. The application of kaolin pigments to the paper industry provided a market that could absorb rapid growth.

Jan 1, 1998

By T. F. Tomb

on' January 6, ,1992, the Mine Safety and Health Administration (MSHA) issued an Advanced Notice of Proposed Rule Making (ANPRM) for diesel particulate (DP). The ANPRM identified five areas where the Agency was seeking additional information to assist in the rule making process. These areas were exposure 'limits, risk assessment, consideration of other information, sampling and monitoring methods, and feasibility. The period for submitting information relative to the ANPRM closed July 10, 1992. Prior to issuance of the ANPRM, the agency was involved in conducting studies to evaluate sampling and control technologies and to gather information with respect to occupational exposures to diesel particulate in underground mining operations employing diesel-powered equipment. Since issuance of the notice, additional studies have been conducted to provide supplementary information in these specific areas. Results of these additional studies indicate that average DP levels in coal mines not using aftertreatment range from 0.9 to 2.1 mg/m3. Aftertreatment devices can reduce these levels by approximately 50 to 90 percent. Studies conducted in metal and nonmetal mines showed average DP levels ranging from 0.3 to 1.6 mg/m3.

Jan 1, 1994

By Victor E. Archer

INTRODUCTION Man is exposed to many agents which induce mutations in germ cells and/or cancer at work, at play, and at home. In this total mix of mutagenic and carcinogenic agents, how important are radon and its daughters? Before man moved into caves and other permanent dwellings, the principal mutagenic and carcinogenic agent to which he was exposed was natural background radiation--cosmic rays, radium and potassium-40 in his food, plus gamma rays and radon from the soil and rocks. When man moved into caves, captured fire, and began to preserve and store foods, his exposure to carcinogens and mutagens took a quantum leap. Carcinogens and mutagens appear to act in the same way, that is, by altering the DNA or nuclear proteins of cells. Most mutagens are carcinogens, and vice versa, so when I say mutagens from here on, I will be referring to both. The relationship of the two is emphasized by the fact that administration of a carcinogen to a group of animals not only increases cancer rates among the exposed animals, but also among their progeny (Tomatis 1979). Environmental Mutagens Smoke from man's fires, overheated foods, and foods preserved by smoking, resulted in ingestion and inhalation of many polycyclic aromatic hydrocarbons--many of which are mutagens. Caves and houses with tight windows and doors tend to collect the radon which is constantly emanating out of soil, rocks and concrete, so man's exposure to the radon daughter component of background radiation increased several fold. Preserving food by salting or pickling with material that contained nitrites and nitrates led to increased ingestion of nitrosamines, which are potent mutagens. When his grains and other foods were stored in slightly damp rooms, fungi or mold would grow on them. Several of these fungi are now known to produce very potent mutagens. The best known of these is aflatoxin B (Ramachandra 1979). It may seem strange that a living organism would produce a mutagen. One might think that it would scramble its own genetic heritage. The reason it does not is that it produces the mutagen in an inactive form. It can be activated only by an animal's enzyme systems after being eaten. When man moved into cities, the collective smoke from wood and coal fires further increased his exposure. That particular smoke has now mostly disappeared, but has been replaced by smoke from automobiles and industry. When man moved into the age of technology, his exposure to mutagens again increased dramatically. Many mutagenic chemicals, from benzene and beta naphthylamine to a long array of pesticides and tobacco products have been added to our environment. Excess deaths from cancer are now being observed among chemists in most industrialized nations. Mutagens are even found in much of our wine, beer, and whiskey (Keller 1980). Some of the chemical mutagens were widely used in food or in other commercial products before their potential was discovered. Striking examples of this is the original butter coloring agent and the polychlorinated biphenyls that have been widely used in brake fluids and electrical transformers. Large quantities of them have been discarded or disposed of in a careless manner--in such a way that many of them have contaminated our food, our ground water and air (Landrigan 1981). In this nation, with the help of several recent laws, we were just beginning to get control of the industrial chemical mutagens. With the relaxing of these laws that is currently going on, it appears that it will be many more years before we really bring chemical mutagens under control. Many nations have yet to come to grips with this problem. On top of this massive array of chemical mutagens we have now added radiation from many artificial sources. For most of us this means medical X-ray and fallout from nuclear weapons testing. Ionizing radiation is one of the most potent mutagens, so it has caught the public eye, and its contribution cannot be ignored. Fortunately, by the time we started using radioactive materials in quantity with the Manhattan Project, we had experience with radium and X-ray (some of it bad); we knew enough radiobiology and enough about methods of radiation protection so that most nuclear laboratories have had a phenomenal record of radiation safety. Radiation is one new technology with great potential for harm that has not exhibited that potential except for a few isolated situations like that of radium dial painters, uranium miners and atomic bomb victims. Uranium miners slipped into this list almost by accident. We could have protected our uranium miners just as well as we did the workers in nuclear laboratories; but we failed to do so. Why didn't we? The reason is simple. The Atomic Energy Commission was charged with protecting the health of their workers. They did not wait for a pile of bodies before they introduced controls. Congress appropriated the money, and taxpayers were willing to pay for the protection against radiation. Miners unfortunately did not work for the Atomic Energy Commission. Although mine operators were ignorant about radiation, the key item was that in the 1950s nobody was willing to pay the extra costs of adequate ventilation to control the high levels of radon and radon daughters in uranium mines. Control was not achieved until new laws and regulations were passed which made it compulsory. BIRTH DEFECTS AND CANCER

Jan 1, 1981

By Gordon V. lewis

The Penjom gold mine treats highly preg-robbing carbonaceous ore by using relatively inexpensive gravity and hydrometallurgical methods. The mine is a joint venture between Avocet Gold Limited, a subsidiary of Avocet Mining PLC, a U.K listed mining company with interests in gold and tungsten, and the Pahang State Development Corporation (PKNP) who receive a 2% royalty. The operating team at Penjom embarked on a programme of innovation during 1998 following a realisation that almost all of the primary ore in the gold deposit was highly carbonaceous in nature. Earlier attempts at desliming and leaching the deslimed product through a normal CIL circuit had failed, and through shear necessity, the team turned to new technologies which were considered most suited to the ore characteristics indicated from pre­feasibility testwork. Between April and September, 1998, the mine introduced three key processes, which combined represent the elements of "The Penjom Process". The gravity circuit was boosted to maximise the capture of leachable sulphide and free gold from the relatively carbon free cyclone underflow stream, kerosene and diesel blanking was introduced to treat the cyclone overflow and RIL (resin-in­leach) technology utilised to replace the existing CIL (carbon-in-leach) circuit. Further experimentation with selective resin in partnership with Mintek of South Africa yielded a significant improvement to the process during 1999. Minix­Dowex resin was introduced mid year to replace a non-gold selective resin, which had been used in a flotation/batch leaching circuit for about nine months. Lower carbon levels in the feed at that stage led to the abandonment of flotation and the introduction of continuous RIL, which has been adopted as the major chemical process at the Penjom gold mine since September, 1999. Given the proven performance of the circuit to date, this process may be considered as a low cost option for the treatment of highly carbonaceous ores, particularly those which are not refractory and contain a reasonable percentage of free gold.

Jan 1, 2000

By P. Piga, O. Sammarco

There is a markedly increasing tendency to design deeper and deeper mines, to use larger amounts of explosive per round, to increase the advance rate of the excavations and so the natural ventilation tends to be more intense in the new mines. For this reason, the mines that make use of powerful mechanical ventilation should also take into account such factors as natural ventilation pressures, especially in the case of mines excavated in high-temperature rocks for which natural ventilation is particularly intense. The results of the studies reported here refer to a very hot mine excavated in an area with a high geothermal flow (the Boccheggiano - Campiano mine, southern Tuscany). At various external temperatures, experimental measurements and analyses have been made of the trend of the thermodynamic characteristics of the ventilation air and of the trends of the air/rock heat exchange along the downcast shaft and along the upcast shaft. These data were then used to work out approximate values of the corresponding natural ventilation pressures. After having identified the most conspicuous variations of the thermodynamic parameters of the ventilation air and the factors causing them, an assessment was made of the repercussions they have on the air flow rates and, above all, on the climatic conditions of the underground excavation sites. The natural ventilation pressures were found not to be constant in time; indeed they change continously and it is difficult to predict the changes. Moreover, it was found that their influence on the ventilation of a section of the mine network is greater if the effect of mechanical ventilation on that section is weaker. In the mine section where the measurements were carried out, some portions were found where the ventilation could become insufficient as a result of the effects of natural ventilation pressures. Finally, some guidelines to be followed in designing hot mines have been put forward which ensure efficient ventilation throughout the network at times with the aid of the natural ventilation pressures, which in certain circumstances may reach very high values in mines of this type.

Jan 1, 1987

By H. Colijn

Introduction Bulk commodity prices are ever increasing. This forces buyers and sellers in world markets to look more carefully at methods for obtaining an accurate accounting of commodity transactions in commerce and materials utilization in processes. Weighing and sampling inaccuracies can result in loss of income, product quality, and cost controls. So weighing and sampling accuracies are extremely important. They are the key components of managing the quantity and quality control aspects of bulk materials handling. This article will confine itself to the weighing systems and will deal with various aspects of system design, calibration, and operations. Emphasis will be placed on new developments and requirements in this field. Weighing methods To measure the gravimetric pull on a body being weighed (the load), the gravimetric force must be countered by an opposing force. Measuring this counter-balancing force thus becomes the measurement of weight. The conventional even-arm balance shows the concept of balancing an unknown mass with an equal known counterbalancing mass. But the loads encountered in industry generally range up to many thousands of pounds. So it is obvious that the even-arm approach is not practical. Thus, with the exception of direct load-bearing load cells, most of the weighing equipment uses some form of lever system. This is usually a combination of first- and second-class levers, to gain a mechanical advantage. These levers permit the load force to be counter-balanced and hence measured within a practical range. Lever systems not only perform this force-reducing action, they also serve to focus the load force at a single point, for convenient measurement. They align the force vertically in one direction so that measurement accuracy will not be affected by unrelated side forces. There are five basic methods of gravimetric weight measurements. That is, there are five basic types of opposing forces. • The first is the standard weight counterbalance. It uses a known weight to counterbalance the load directly or through a lever system.

Jan 9, 1988

By R. R. Fernández

The Newmont roasting plant in Carlin, Nevada, commenced operating in December 1994. Over the years, refractory ores and pyrite concentrates from different gold deposits constituted the feed to the facilities. Historical plant performance indicated that the roasting temperature was the main variable affecting the structural characteristics of the calcine, which in turn affected the recovery of gold by cyanidation. Gold recovery as a function of roaster temperature has been closely monitored since October 2000. The original design temperature was 550° C. Lower roaster temperatures of around 500° C resulted in a gold recovery increase of more than six percent. This increase was directly related to an increase of the surface area of the calcine. The implementation of an ?intelligent? process control system helped significantly in achieving steady low roasting temperatures, thus obtaining high gold recoveries of 92 to 93 percent. Under these conditions, several roasting campaigns with high-arsenic-containing ores were conducted, which resulted in a significant decrease in gold recovery. The reduced gold recovery was caused by the loss of surface area (e.g., porosity) of the calcine as the arsenic content of the roaster feed increased.

Jan 1, 2010

By R. T. Swinderman

This paper discusses a series of tests designed to help answer the age old question: ?How much does the belt cleaner wear my belt?? The experimental set up and test method are described. The main variables are: belt cleaner blade materials, cleaning pressures, cleaning angles, belt speeds, and belt top cover grade. The bulk material used is a standard test-grade silica sand. The measured results include: blade mass loss, belt mass loss, and cleaning efficiency.

Jan 1, 2010

By C. T. Twort

As technology and economic conditions allow mines to operate at ever greater depths, increasing demands are placed on the environmental engineer to adjust the capacity of the installed mine . - refrigeration systems. At the same time the engineer must satisfy the changing legislation, which demands that developments are carried out in as an energy efficient and environmentally accept- able manner. Following the trends outlined above, this paper is written to give an overview of the current and potential future refrigeration technology available to the mining industry. The effects that may be produced by the adoption in mining applications of the new generation of 'green' refrigerants are examined both at the design stage and when considering the viability of retrofitting existing systems so that they comply with the Montreal Protocol. An introduction to the concept of Total Energy Warming Impact (TEWI) is provided, with an explanation of its use in optimising system design and performance, and its incorporation as part of an environmental audit strategy. The paper concludes with a discussion of innovative refrigeration techniques and the possible future developments in legislation.

Jan 1, 1997

By C. R. Zegarra

Extraction of manganese, gold, and silver from a low-grade manganiferous-silver ore was investigated by thiourea leaching followed by standard cyanidation. The levels of reagent concentrations in this investigation were 0.0 -1.0 M thiourea and 0.0 -1.0 M sulfuric acid. Temperature and agitation speed were maintained at Z5 °c and 300 rpm, respectively. The dissolution of gold, and silver was shown to be dependent mainly on sulfuric acid and thiourea concentrations. In general, 50.0 % Ag, 98.0 % Au, and 75 % Mn were recovered from a Mn-Ag ore by thiourea leaching. Overall silver extraction of 98.0 % was obtained by cyanidation after thiourea leaching. Thiourea leaching of sodium bisulfite leach residues was also studied, and the total extraction of gold and silver were 97 % and 40 %, respectively. Finally, a two-stage thiourea leach was also investigated.

Jan 1, 1988

By Raghoottama S. Pandurangi, Mohindar S. Seehra

A critical examination of the published results on the hemolytic ability of different forms of silica viz, quartz, cristobalite, tridymite and amorphous silica is made and it is concluded that quartz, cristobalite, and tridymite have nearly equal longterm abilities (within ±15%) but much larger than the hemolytic ability of amorphous silica when correctly compared on a per unit surface area basis. Also, a one-to-one correlation appears to be valid between the hemolysis and fibrosis studies. New results on the photoacoustic spectroscopy of amorphous silica particles heat-treated at 100, 200, 400, 550, 700, 820 and 1050°C are presented and it is observed that the intensity of the sharp silanol band at 3745 cm-1 and hemolysis by these particles have nearly the same temperature dependence. In contrast the intensity of the bulk IR modes (viz. the 797 cm-1 band) does not show any significant temperature dependence. These observations demonstrate that the surface SiOH species are involved in hemolysis by silica particles. Key words: silica polymorphs; hemolysis; silanol species

Jan 1, 1991