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By Ramamritham Sridhar, Vaikuntam I. Lakshmanan, Dan A. Macki

Historically, introducing new technology to the mining industry has been problematic. In general, the industry is reluctant to take risks with new technology because it is already heavily tied to risk, even using existing technology. Risk in the orebody itself can be substantial. The company is dependent on drill hole patterns that are expected to define what is underground, and process test work is often based on drill cores and other samples, which occasionally produce surprises. And even well-proven processing techniques can blindside the producer, resulting in embarrassing and costly difficulties. But if the industry is to grow in knowledge and become more efficient, new ideas must be introduced. How to introduce new technology is the essence of this paper.

Jan 1, 2001

By J. A. Herbst, K. N. Han, P. B. Queneau, S. W. Asihene

As hydrometallurgy matures as a technology, more of its existing process knowledge will continue to be summarized in the form of detailed mathematical models. This development is happening at a time when major improvements in computer hardware have reduced the cost of computing. The opportunity then exists, through the solution of these process models, to design, control, and optimize hydrometallurgical plants on the basis of the physics and chemistry of its processes and less on empiricism. In this paper, a review of the current capabilities of sensors and phenomenological models for selected hydrometallurgical processes is presented. Future trends, in terms of the control and optimization of hydrometallurgical plants, are then explored. The possibility of simultaneously optimizing plant design and associated process control system performance is discussed.

Jan 1, 1993

By T. van Sandwijk, G. Van Weert, E. Molleman

This paper reports on test work that explored the dissolution/precipitation reaction: ZnS + 2HCl - ZnC12 + H2S, which is part of a process used in the production of pure ZnS. The research focused on the influence of proton activity on the dissolution of zinc concentrates obtained from the Brunswick Mine No. 12 in Canada (Brunswick Mining & Smelting); the Red Dog deposit in Alaska (Cominco Ltd.); and the Tara deposit in Ireland (Outukumpu Zinc). A comparison between the results of the experimental dissolution as a function of pH and the dissolution predicted by thermodynamics suggest that the three concentrates contained sig¬nificant amounts of the more reactive mineral wurtzite, although XRD analysis showed mainly the presence of the mineral sphalerite.

Jan 1, 1999

By M. Scaggs

"Respirable dust in underground coal mines has long been associated with lung diseases, and regular dust sampling is required for assessing occupational exposures. At present, respirable dust concentration and crystalline silica content are commonly determined, but considering recent and yet unexplained increases in the incidence of lung disease amongst miners in specific geographic regions, more information about specific dust characteristics is urgently needed. While particle-level dust analysis is ideal, it is impractical for large numbers of dust samples because it is both time and cost intensive. Thermogravimetric analysis (TGA), however, is an alternative option, which offers the ability to determine the total coal to mineral mass ratio in a dust sample – analogous to proximate analysis of bulk coal samples for determining ash content. Here, preliminary development of a TGA method for this purpose is presented. The method is being developed to evaluate dust collected on mixed cellulose ester (MCE) filters using approved permissible sampling equipment. INTRODUCTION Based on the particle size, airborne mine dust can be classified in three categories: inhalable dust (< 100 µm in size), thoracic dust (< 25 µm in size), and respirable dust (< 5 µm in size) (Ramani et al., 2003). The World Health Organization (WHO, 1999) defines inhalable dust particles as those which can be breathed into the nose and mouth, and thoracic dust particles as those which can penetrate airways of the head and enter the airways of the lung. On the other hand, respirable dust particles can penetrate beyond the terminal bronchioles into the gas-exchange regions (alveoli) of the lungs (WHO, 1999). Hlavay (1992) reported that the seriousness of the damage in the lungs and respiratory tract is based on amount of dust remaining in these organs, and the amount of dust depends on the extent of dust exposure, the size distribution of the dust particles, and the capability of the body for dust elimination. Inhalation of respirable coal dust by miners can cause a disabling and potentially fatal lung disease which is called coal worker’s pneumoconiosis (CWP). Silicosis is another fatal lung disease caused by inhalation of respirable silica dust. In CWP and silicosis, dust particles deposit in the lungs, damage the lung tissue, and ultimately cause scarring which cannot be reversed (Colinet, 2010). While overall incidence occupation-related lung disease amongst coal miners in the US has been declining for over 40 years, it appears that there has been a recent increase in specific locations in Central Appalachia (CDC, 2006; Pollock et al. 2010; Suarthana et al., 2011). Although this trend is yet unexplained, one theory is that particular dust characteristics in these locations may be a factor (Hassan and Lau; Page & Oraniscak 2002). For example, several studies have indicated that different coals may generate different amounts of respirable dust (e.g., see Page, 1993 and Litton and Page, 1994), and the surrounding geology may also play a role in terms of the types of dust particles generated. Although respirable dust concentration and crystalline silica content are commonly determined as part of regulatory compliance sampling, more information about specific dust characteristics (e.g., size, shape and composition) is urgently needed."

Jan 1, 2015

By A. Singh, C. Da Corte

"South Africa possess the biggest fluorspar reserves in the world followed closely by China. In light of the current commodity downturn this paper explores the use of Dense Media Separation (DMS) as a coarse pre-concentration method for two fluorspar deposits located in South Africa in which the dominant gangue is carbonate present in the form of dolomite and calcite. Heavy Liquid Separation indicated that conventional pre-concentration of the drill core samples from both deposits would result in unacceptably high fluorite CaF2 losses. At a maximum CaF2 loss to floats of 5% the benefit of DMS would be economically marginal and difficult to justify as a conventional pre-concentrator. In light of cashflow constraints, a twin flowsheet was proposed for the sole purposes of upfront cash generation in which the majority (67-77%) of the CaF2 would report to a high grade flotation plant in 38-41% of the mass whilst the rejects would be stockpiled for flotation at a later stage. Considering the proposed twin flowsheet approach the high grade product split was achieved using DMS and this paper documents the challenges encountered and results achieved. INTRODUCTION Fluorspar is the commercial term for the mineral fluorite (calcium fluoride, CaF2). Worldwide production of fluorspar is dominated by four countries namely China, Mexico, Mongolia and South Africa. Although South Africa is the fourth largest producer, it has the largest fluorspar reserves closely followed by China (U.S. Geological Survey, 2017a). Fluorspar is broadly categorized into two grades namely acid grade also referred to as acidspar (>97% CaF2); and sub-acid grade (ceramic and metallurgical grade) commonly referred to as metspar (=97% CaF2). Acid grade fluorspar is used for the production of hydrofluoric acid (HF) which in turn is used for the manufacture of fluorocarbons and semi-conductors in the electronics industry; metal processing; the production of insecticides, herbicides and cleaning detergents, and the manufacture of uranium tetrafluoride used to concentrate the uranium isotope 235 for use as a nuclear fuel (British Geological Survey 2010; Miller 2001). Ceramic grade fluorspar (85-95% CaF2) is used in the ceramic industry as a flux and opacifier in the production of glass and enamels. Ceramic grade fluorspar is also used to make coatings for welding rods and as a flux in the steel industry. Metallurgical grade fluorspar (60-85% CaF2) is primarily used in the steel industry as flux to reduce the melting temperature and remove impurities in steel making. Similarly metallurgical grade fluorspar is also used as flux in cement production to reduce energy consumption (British Geological Survey 2010; Miller 2001)."

Jan 1, 2018

By R. L. Grayson

In 1995, Congress abolished the Bureau of Mines in the Department of Interior but preserved the safety and health research functions being performed at the Pittsburgh and Spokane Research Centers. These functions were transitionally housed in the Department of Energy before permanently merging with the National Institute for Occupational Safety and Health (NIOSH), Department of Health and Human Services, in October 1996. Since the merger of the former Bureau with NIOSH, there has been an active evaluation of ongoing research activities, significant interaction with stakeholders, and the development of a process leading to "data informed" priority setting. This presentation will review current surveillance information concerning the level of injury and disease from mining work and will discuss how research priorities are evolving to improve the contribution of research to the prevention of injury and disease.

Jan 1, 1998

By P. Bottomley, M. Matthews

Maintaining an acceptable thermal environment in South African gold mines becomes increasingly difficult as mining progresses to greater depths where higher virgin rock temperatures are encountered. Current environmental practice offsets the resulting high heat loads by installing large refrigeration plants. However, with the continued escalation of refrigeration costs, it has become necessary to examine other methods for economically combatting the underground heat load. The Chamber of Mines Research Organization has recently been pursuing a programme to devise methods of reducing the flow of heat into underground workings at source. Although there are several sources of heat (such as machinery, men, and explosives), the most significant is that from the rock mass surrounding the workings (Bluhm et al., 1986a). The main thrust of the work has therefore been directed at predicting and devising methods of reducing this heat source. A great deal of theoretical work has been carried out on the prediction of underground heat flow. From a review of this work (Bluhm et al., 1986b) it became apparent that there are two major aspects which require attention, namely algorithms for predicting the heat flow around the advancing stope face, and a correlation of the theoretical work with accurate empirical data. In order to remedy this situation, new theoretical models have been developed (von Glehn and Bluhm, 1986), and heat flow measurements have been made in both a conventional stope (Bluhm et al, 1986a) and in a backfilled stope (Matthews u., 1987). A number of methods for reducing rock heat flow are being examined. These include the insulation of intake airways (Bottomley, 1985 ), backfilling with waste material of the worked out areas, and alternative approaches to the design of mining layouts, the mining method, and the choice of cooling strategy. This paper highlights the heat load reductions that can be achieved by backfilling the worked-out areas and by adopting concentrated mining. The first part of this paper summarizes the results of the measurements obtained in the conventional and backfilled stopes. The theoretical models are then described and comparisons are made with the measured values.

Jan 1, 1987

By W. Lin

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Jan 1, 1997

By L. Hales

Neural networks are a generalized, multivariable non-linear modeling technique that can be used to model mineral processing operations. Neural networks will be described as will their use in modeling column flotation. Optimization of column flotation will be explored and discussed by using the neural network column models.

Jan 1, 1996

Humic acids adsorb on coal and depress coal floatability in the acidic pH range. In alkaline solutions, their effect is not pronounced. In the neutral pH range, a second small addition of kerosene plus MIBC leads to a significant increase in coal yield and better selectivity. Humic acids present on oxidized coal surface were found to be responsible for the inhibited floatability of the? coal. As expected, the flotation of such oxidized coal also strongly depends on the method of pH adjustment.

Jan 1, 1988

By Joseph M. Hans

INTRODUCTION The decontamination of a uranium mill site is principally an earth moving task. The task can be completed effectively and efficiently by selecting the proper earth moving equipment and using that equipment within its particular constraints for decontamination work. A considerable backlog of experience concerning earth moving equipment selection and use was acquired during the decontamination work conducted at the former Shiprock, New Mexico, uranium mill site. This experience was acquired by trial and error while decontaminating over a wide range of depths and different types of terrain. Many different types of excavation equipment were available to the Shiprock decontamination project because the Navajo Engineering and Construction Authority (NECA) heavy equipment operator&apos;s school was doing the decontamination work and a variety of equipment was needed for training. The equipment is described and its general use for decontamination is discussed. Its on-the-job use for decontaminating the Shiprock millsite is presented. [EARTH MOVING/ANCILLARY EQUIPMENT DESCRIPTION AND DECONTAMINATION CONSTRAINTS] Tractor-Scrapers The most commonly used scraper is the bottom-dump type because it is highly mobile and can dig, carry, and spread loads. In this type a tractor is connected with a yoke to a scraper bowl (Figure 1). The bowl is essentially a rigid box that pivots around the rear axle, opening to the front. A hardened steel knife, or bit, is attached to the leading edge of the bowl. When scraping, the bit penetrates and forces the earth overlying the bit edge into the scraper bowl as the scraper moves forward. When the bowl is full, it is closed by lowering a closure or apron against the cutting bit. The load is dumped while moving, by raising the apron and forcing the load from the bowl with a crowd, or ejector. The height of the dumped load is controlled by adjusting the bit height when dumping. Scrapers of this type generally do not have enough power to scrape up loads unassisted. Loading assistance is generally provided by a crawler tractor that pushes from the rear against the scraper&apos;s push block. Some scrapers are made self-loading by adding an additional engine for the extra power needed for the load pick up. Another commonly used self-loading scraper uses a loading elevator (Figure 2). The elevator consists of two roller chains carrying crossbars. The elevator is rotated when scraping and the crossbars cut the earth above or in front of the bowl bit, forcing the load into the scraper bowl. No apron is used on elevating scrapers. The load is dumped by partially retracting the bowl floor and pushing with an ejector. Scrapers have some undesirable characteristics when used for decontamination work. One characteristic is that a clearance space exists around the apron when it is in its closed position. Part of the load (especially sandy soils) dribbles through the

Jan 1, 1981

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

To reduce their sulfur emissions, many coal-fired electric power plants use wet flue-gas scrubbers. These scrubbers convert sulfur oxides into solid sulfate and sulfite sludge, which must then be disposed of. This sludge is a result of reacting limestone with sulfur dioxide to precipitate calcium sulfite and calcium sulfate. The majority of the sludge is simply landfilled, but with increasing landfillimg costs this can cost the plant millions of dollars per year. As a result, this option is rapidly becoming less attractive. Producing marketable materials from the sludge is a far more promising avenue, provided that the products can meet the necessary specifications at a reasonable cost. In this paper, a method is described for using froth flotation and water-only cyclones to remove unreacted limestone from scrubber sludge. The water-only cyclone was found to be very effective for removing the coarser unreacted limestone, grinding ball chips, gravel, and similar coarse impurities. Froth flotation was found to remove fine unreacted limestone, with a minimum of reagent addition.

Jan 1, 1995

By A. Raviprasad, B. Das

Copper ore from the Rakha Copper Concentrator (India) was successfully floated using LIX-65 NS as the collector. The beneficial role of this reagent was clearly demonstrated in hatch-flotation tests. From a feed containing around 1% Cu, it was possible in a single-stage flotation to obtain a 23.7% Cu concentrate with a recovery of more than 90%. The plant now uses rougher, scavenger and a two-stage cleaning process. The tests demonstrated that LIX-65 NS is superior to conventional xanthate for the recovery of copper from the Rakha ore.

Jan 1, 1997

By R. Buchan

A number of mineral processing techniques have been adopted for the separation of the plastics making up a typical beverage bottle, and a complete flowsheet developed. Thus, size reduction, heavy media separation and flotation were used to separate PE, PVC and PET from their mixtures with cellulose fibers and aluminum, which makes up the cap of such bottles. It is shown that while heavy media separation allows the separation of a PVC/PET mixture from the solid waste, froth flotation can be readily used to separate PVC and PET from a mixture of the two. For this purpose, the differential action of an alkaline aqueous solution (PH=II) which contains methanol and MIBC as surface tension control agents has been found to be a suitable flotation medium. This paper reports some aspects of the flotation flowsheet developed for the separation of plastics from municipal solid waste mixtures and PVC from PET.

Jan 1, 1995

By Kumara S. Rachamalla

Mineral activity in Ontario represents an annual production in excess of $4 billion. The Ontario government encourages the mining industry to undertake mineral development through grant programs and incentives offered by mineral resource taxation. Computers are playing an increasingly important role in improving productivity in the administration of incentive programs and the Mining Tax Act in Ontario. This has meant speedier processing of grant applications and tax returns which is resulting in a streamlined approach to incentives and taxation in Ontario. The use of computers has resulted in significant contributions to key areas of concern such as assessment of mining tax returns, analysis of the changes, if any, to the Mining Tax Act and modeling of the Ontario Mineral Exploration Program (OMEP). Implementation of state-of-the-art technology such as Local Area Networks (LAN&apos;s), fourth generation languages and integrated micro-mainframe information processing has resulted in improved productivity as well as lower costs. As a result, the respective services provided to the mineral industry by these two programs are now delivered in an efficient and cost-effective manner utilizing the latest available computer technology.

Jan 1, 1986

By Y. J. Wang

A subsystem-based approach to the characteristic curves for a multiple fan ventilation system is presented. The ventilation variables and their relationships associated with a fan branch are considered as a subsystem of the multiple fan system. For each subsystem, the solution curve is generated by replacing the fan with a hypothetical pressure source or, alternatively, by adding a hypothetical pressure source without removing the fan. The projection of the solution curve onto the coordinate planes results in two classes of subsystem characteristic curves: pressure-vs.-quantity and quantity-vs.-quantity. The subsystem characteristic curves are described and illustrated through example ventilation systems. These curves are also discussed using the network equations of a general multiple-fan system.

Jan 1, 1993

By Michael J. Mankosa

Carpco has recently evaluated the use of various mineral processing techniques for secondary materials recovery. These applications include recycled foundry sands, plastics and secondary metals. This paper describes different recycling applications and the associated separation solutions. Results from extensive laboratory-and pilot-scale test work in each area are discussed. Industrial installations resulting from this test work will be presented. A detailed description of an industrial installation patented by Carpco for the recovery of plastic and metallics from current waste by-products is presented.

Jan 1, 1997

By Stephen H. Partney

Waste clay ponds are a necessary part of phosphate rock beneficiation. They are large, averaging 2.6 km2 (1 sq mile). They are unsightly in that they protrude 6 to 15 m (20 to 50 ft) above natural grade. Stabilization and reclamation is slow and they have had a history of catastrophic failure. Florida has never published a specific rule regarding the configuration or height of these ponds. But it has enforced several policies along these lines. The phosphate industry has been forced to make major monetary decisions that affect mine economics for decades. The Florida Bureau of Mine Reclamation believes that the direction of regulation has been solidified but changes are still anticipated. Phosphate rock has been mined in Florida since 1890 (Fig. 1). Three notable technological changes occurred in the industry that led to major shifts in mining technique and volume. By about 1915, hydraulic mining had been replaced by centralized washers. Hydraulic mines usually started at an outcrop in or adjacent to a stream of the pebble zone. Water was pumped out of the stream through high-pressure monitors and sand and clay were washed away from the pebble. Mobile grizzlies and screens were used in conjunction with animal and human labor to concentrate the pebble and haul it away. Populations were sparse and the clays washed into the stream were considered an acceptable price for the commerce. The clays were not voluminous because the pebble zone typically contained relatively small amounts of them. Machines largely replaced animals by 1910 and provided greater efficiency of production. Centralized washers replaced mobile trommels. They allowed greater ease of access to shipping routes by rail. Some clays were placed in mine cuts from 1915 to 1930. Some were dammed off to increase the capacity of a given site. Some of these also failed, leading to clay plumes that were visible all the way to the Gulf of Mexico. By concentrating the waste clays (slimes) in impoundments, the solids concentration had increased, making plumes persistent for long distances. There were complaints. But there was no litigation against the companies during that time. In 1930, flotation technology allowed the recovery of the phosphate from deeper zones. This was because the "concentrate" size phosphate rock was in the sand-size range and could not be screened out. Centralized beneficiation plants grew into a three-step process - washing and screening, feed preparation and flotation (Fig. 2). Reagent storage, safety and the flotation cell complex made the plants into large capital installations. Larger draglines were required to dig deeper into the matrix. These had dramatically larger production capacities, which were then figured into the overall material balance for a given plant. The number of operators shrank and the production per operator grew. Larger areas were being bermed off for waste clay storage. An economic incentive became apparent for storing as much waste clay as possible in each settling area. At the same time, the population was steadily growing and more eyes were watching the activities of the phosphate mines. Phosphate mining, focused on production and profit, was earning a bad name from its neighbors. When the subject of phosphate mining

Jan 1, 1998

By Bhaskar B. Thapa, Michael T. McRae, Michael J. Teske, Richard M. Nolting

Packer test data and tunnel in?ow observations are used to show that the distribution of equivalent hydraulic conductivity obtained for a rock mass from borehole packer testing will be biased if the orientations of the planned tunnel and testing borehole differ. Furthermore, test results show that the distribution of equivalent hydraulic conductivity is different in various geologic sub-units at the same site. The impact on in?ow of the major uncertainties, including conductivity, head and specific yield, is illustrated to be amenable to a combined analysis using Monte Carlo simulation.

Jan 1, 2003

The issues involved in mine closure are usually complex, and the risks are significant. Although environmental risks are paramount, other issues such as safety, community, legal, fiscal and technical factors need to he taken into account. This paper describes a simple empirical model based on the concept of the closure risk factor, which will enable decision-makers to analyze the mine closure risks at any site, regardless of the complexity of the issues and the scale, scope and location of the operation. The model enables all the issues to be captured and their individual and collective risk quantified. A number of case studies in Australia and the Pacific that illustrate the usefillness of the model are presented.

Jan 1, 2002