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By William X. Chavez

The Mantos Blancos copper-silver district is located in northern Chile about 45 kilometers northeast of Antofagasta, as shown in Figure 1. Disseminated and veinlet copper and copper-iron sulfides containing economically significant silver values are hosted by andesitic to rhyolitic volcanic rocks of probable Jurassic age (Chavez, 1983). Field, mineralogical, textural and lithochemical evidence show that three major alteration types may be recognized within the district: (1) district-wide sodium metasomatism, manifested as albitization of feldspars and development of albite veinlets and pore-fillings, (2) local to widespread, incipient to intense addition (chloritization) or removal (bleaching) of magnesium and iron and (3) local to widespread, moderate to intense hematitization, usually spatially associated with bornite-digenite-covellite (as specularite) or digenite-covellite-chalcocite (as red hematite staining with or without specularite) mineralization. Carbonatization, occurring as veins, veinlets, vesicle fillings and irregular patches of calcite, varies in magnitude of development but is widespread. Sericitization of feldspars and groundmass is only locally intense yet is generally present as incipient alteration throughout the district. The district-wide albitization of the Mantos Blancos volcanic sequence has altered what were originally more potassic and calcic, less sodic, rocks to what are now more properly referred to as keratophyres (Battey, 1955; Gilluly, 1935, Hughes, 1975). The petrographic and lithochemical characteristics of the three major alteration types noted above are summarized below.

Jan 1, 1984

By L. J. Hoover

The objective of this study was to assess the health and environmental impacts of fluidized-bed combustion (FBC) of coal, specifically as applied to baseload generation of electrical energy by utilities. The study* was a short-term effort that based its analyses on information derived from the experience of the group or quickly obtained from the literature. The approach was to compare Atmospheric Fluidized-Bed Combustion (AFBC) and Pressurized Fluidized-Bed Combustion (PFBC) with two current technologies: low-sulfur coal combustion (LSC) and flue gas desulfurization (FGD) used with high-sulfur coals. A wet-limestone process was selected as the FGD technology. The impacts compared involved not only health and environment but also sociology, resource use, and dollar cost. Conditions for comparison were centered around a nominal date of 1988, when initial operation of commercial AFBC plants may occur. The PFBC has a later introductory date, a nominal 1995 (its impacts relative to other competitive technologies now in the R&D stages were not compared.)

Jan 1, 1978

By Ditend Tesh, Mallikarjun Pillalamarry, Nikowa Namate, Harmony K. Musiyarira

Many reports have been written about the issues surrounding small scale miners’ challenges in Namibia; yet little has been done to address these challenges. There has been a fragmented approach to address these challenges. Various government arms and donor organizations have utilized piece meal methods in the past in trying to make improvements on the productivities across the sector, but with no meaningful success. This has led to the design and implementation of inappropriate technologies and support services for the sector. The structures of many of the semi-precious stones mining businesses are informal, with very little royalties received by the government. Miners often work informally or illegally and they fear government interference and they distrust outsiders, resulting in them withholding production information. The presence of small scale miners is quite often associated with major challenges, including poor safety and environmental management standards, the spread of communicable diseases and poor working conditions. The majority of the miners employ uncontrolled extraction techniques which damage the crystals and mineral specimens, resulting in intermediate and final products of low quality along with high wastage at the extraction stage. The vision of the Namibian government is to expand the range and value of semi-precious stones and jewelry products processed within Namibia, while curbing illicit flows of raw stones. This will simultaneously secure maximum benefit for the country. This study investigated the interventions aimed at making the small scale mining sector in Namibia sustainable. A baseline study was conducted to analyze the current situation and characterize the industry, including a SWOT analysis. Information was collected through questionnaires, interviews, consultative meetings, field visits and workshops in order to profile the sector. The baseline study results were used in developing interventions for improving artisanal and small scale mining operations. The main challenges for the Namibian semi-precious sector were identified as: factual information about raw material resources and its beneficiation are insufficient or not available, lack of skills, lack of education and access to finances, rudimentary exploration and mining practices, trading and logistics that are not functioning effectively and inadequate sector governance. One key finding of this study was that Namibia is not benefiting through value addition due partly to illicit flows of the uncut stones and to the fact that lapidary is not much pronounced to a greater extent. The following strategic interventions were identified as key in ensuring the sustainability of the small mining sector in Namibia: conducting geological assessment to identify new deposits and quantify the existing ones, improving exploration and mining practices, investing in education and training, creating an enabling environment and improving the sector governance and strengthening the sector organization and supporting the infrastructure.

Jan 1, 2017

By R. A. Matuszak

Throughout the history of power excavating machines, engineers have continuously tried to shape the main drive speed-torque characteristics to provide an optimum performance from each main motion. Selection of prime mover for the various motions has been the subject of many engineering studies and most forms of energy conversion have been tried. A new form of electrical power conversion looms on the horizon' as the most optimum yet. Controlled frequency operation of a squirrel cage induction motor increases the reliability of the most reliable form of energy conversion (electrical) found thus far and at the same time improves the performance characteristics.

Jan 1, 1977

By Roger Malmström, H. Heden, Kjell Lidin

INTRODUCTION LKAB was formed at the turn of the century when the railways between the ore fields and harbors were built. The mines are situated north of the Arctic Circle in Sweden. Kiirunavaara is the largest mine, with a pro¬duction capacity of approximately 30 Mt/a. Malm¬berget has a capacity of about 12 Mt/ a. Both are under¬ground mines. Svappavaara, the only opencast mine currently in operation, has a capacity of about 4.5 Mt/a. The ore harbors are at Narvik for the Kiruna and Svappavaara mines and at Lulea for the Malmberget mine (see Fig. 1). Production in the form of finished products is shown in Fig. 2a, b, c, and d. Due to poor ore markets in re¬cent years, production and shipments have been cut back, but there was a positive swing in 1978. LKAB has been 96% state-owned since 1957. In addition to the iron mines in northern Sweden, LKAB has subsidiaries in central Sweden which produce sulfide ores, quartz sand, and uranium (Fig. 3). The mining methods employed are opencast bench stoping at Svappavaara and sublevel caving at Kiirunavaara and Malmberget. GEOLOGY The Kiirunavaara ore body is 4000 m long and av¬erages about 90 m wide, with variations in width from a few meters to around 150 m. The ore has been ex¬plored by deep drilling down to about 1000 m, but mag¬netic measurements indicate a depth of at least 1500 m. The Kiirunavaara ore is oriented in a north-northeasterly direction with a number of ores in the boundaries be¬tween the wall rock types. The ore in Kiirunavaara is mainly a fine-grained magnetite with a varying content of fine-grained apatite. The apatite content of the ore decreases with increasing depth. The other ores are all apatite-bearing and a couple are hematite ores (Fig. 4a, b). The ores are sedimentary, tilted, and tectonically de¬formed. They have a lateral dip of 0.87 to 1.2 rad (50 to 70°). The contacts between ore and wall rock are distinct and sharp, but both the hanging wall and the footwall are brecciated and impregnated with magnetite. The footwall of the Kiirunavaara ore consists of syenite porphyry with a low quartz content and rela¬tively good strength; the hanging wall consists of quartz porphyry. Both types are known as Kiruna porphyries. The ore at the boundary with the hanging wall is often rich in kaolin. There are a few veins of syenite porphyry running through the ore, which has a few major faults (Fig. 4c, d). There are two sharply delineated ore grades in Kiirunavaara: low phosphorus ore with less than 0.1 % phosphorus (about one-third of the ore) and high phos¬phorus ore with greater than 0.5% phosphorus. The iron content is 67% in the low phosphorus ore and 60% in the high phosphorus ore. These ore types are sold as different grades and so are kept separate during mining. MINING AT KIIRUNAVAARA The Kiirunavaara and Luossavaara ores were first mined using opencast bench stoping in 1902. When mining costs rose owing to higher waste removal, under¬ground methods were adopted. In the mid-1950s, the ores were still being mined on the surface at the same

Jan 1, 1982

By Peter Dietrich, Joseph DeMello, Norbert Fuegenschuh, Kerwin Hirro, Jeff Brandt, Mike Cole

This paper presents a successful case history of the ground improvement efforts and excavation of twenty-three cross passages between twin bore tunnels driven by EPB tunneling machines in Los Angeles, California on Section 1 of the Westside Subway Extension. Unique and complicated ground conditions local to the tunnel alignment include San Pedro sands, siltstone/claystone Fernando Formation, and zones of “asphalt impacted soils.” To provide water cut-off and soil stabilization, jet grouting was performed prior to TBM excavation at the location of many of the cross passages. However, upon investigating the cross passages prior to excavation, the subsurface conditions required additional measures and SEM tools to ensure successful completion of the project.

Jun 13, 2023

Previous models describing the aggregation of polymer coated particles fail to take into account the fact that there are a limited number of sites onto which a polymer segment can adsorb, called ?active? sites. Thus, the collision efficiency is a factor not only of the fractional surface coverage, but also of the number of active sites. In this study, a physical model of the flocculation system was devised in which the number of these sites could be varied, in order to study the effect on particle aggregation.

Jan 1, 1987

When solid pillar is not left to separate different mining levels in underground mine with high dip angle deposit, waste rock in the backfilled stope could be a safety hazard to future mining activities on levels above or below the backfill. Different backfill methods can be used to eliminate this hazard according to the deposit shape and mining method. Building concrete pillar in ore drift of each mining level is one of them. Concrete pillar had been constructed in underground mines based on operational experience. Little design literature and pillar performance data can be found. At Great Basin Gold Hollister Mine, over two thousand feet of concrete pillar had been constructed. The project started with engineering design which combined civil engineering concrete design and the specialties of underground construction. Time Domain Reflectometry technique was installed to monitor the pillar movement and concrete cylinder samples were collected and tested for quality control. Engineering design, underground construction, quality control and concrete pillar monitoring, as well as precious concrete mixing data from years of experience are fully covered in this paper to give a general frame of concrete pillar method.

Jan 1, 2010

By Marlies Grimmer, Frank Amo Boateng

One of the challenges of mining is the concentration of heavy metals it releases into the environment through a phenomenon called Acid Mine Drainage. Freiberg is no exception due to its long mining activities. The European Union proposes that all rivers and streams must be in a good ecological status by the year 2027 but this would be difficult for large water sources as it would be economically unviable. Consequently, the approach of treating these waters at point sources would be of immense help and hence this column experiment on mine water treatment with carbon sorbents to remove zinc form the Rothschönberger Stolln. For this experiment three resins namely, APTsorb, activated coke, charred fermentation residues (which was produced by the Freiberg University of Mining and Technology) were analyzed through a simple column experiment to determine their sorption capacities. Through their sorption capacity as this experiment seeks to ascertain: we are able to make suggestions scientifically on the best material among the three for the future design of a treatment plant for the RSS. After the experiment whereby a 10 ml peri glass column was used, material A: APTsorb showed the least adsorption capacity (0.01 meq/g) and this could be attributed to the fact that the resin works well under pre-determined parameters such as pH and surface area. Material B: Activated coke showed a better sorption capacity (0.53 meq/g) in comparison to the basis value used for this experiment. Material C: charred fermentation residue which was produced by the University showed the most efficient capacity of (1.69 meq/g). This in comparison with the value used as the basis for this experiment showed that material C (charred fermentation residue) is very efficient for zinc sorption. pH values measured at the effluent of all the experiment were slightly higher than the pH measured in the initiating water.

Feb 1, 2024

By Naoko Shimazaki, Andre Xavier

Over 10 million tourists have visited Vietnam in 2016. Travel and tourism accounted for 9.3% of the country’s Gross Domestic Product (GDP) in 2014. At the same time, as with many other resource-rich developing countries, Vietnam has been developing its extractive resources sector as a means of promoting the country’s social and economic development. In 2015, mining was the third largest contributor to GDP, and accounted for 8% of Vietnam’s gross domestic product. Vietnam is the third largest mineral producer in SE Asia. Although it produces zinc, nickel, bauxite, and manganese, coal mining is its most developed sector. The country has over two hundred coal mines, and total reserves of approximately 6 billion tons. Quang Nihn Province, where the World Heritage Site Ha Long Bay is located, is a very important tourism destination. It is also a coal-rich region where mining extraction and processing have been active since the early 20th century. Vietnam is signatory of the United Nations Sustainable Development Goals (SDGs). The country is aware of the importance and the challenges involved in managing the extractive sector in a way that does not undermine its tourism industry and yet that contributes to the country’s sustainable development. To this end Vietnam is taking actions towards implementing more advanced coal-mining extraction and processing techniques. The country is furthermore promoting a responsible mining sector, and is investing in programs that foster environmental protection and sustainable tourism. This paper examines the case of the Ha Long Bay region and the project involved in relocating the Hong Gai coal preparatory factory from a seafront area to a mountainside area. This paper provides a preliminary review of the initiatives adopted by the government of Vietnam to address the existing challenges that have resulted from a focus on promoting the country’s socio-economic development through the exploration of its rich coal endowment. Furthermore, it also describes Vietnam’s legal and policy frameworks. In conclusion this study identified that Vietnam has drafted a National Action Plan to implement the Sustainable Development Goals. The country is also taking an integrated approach to implementing the SDGs agenda and that it is assigning responsibility to a variety of ministries to achieve SDGs’ specific targets. Furthermore the country is changing policies and the legal framework in order to facilitating the execution of the work of agencies that are responsible for implementation, regulation and enforcement. In this respect, the approval of the National Action Plan on Sustainable Development Goals is another important step in that direction. While the decision of supplying its internal market with high quality coal helps minimize negative environmental impacts in Vietnam, exporting low quality coal to other countries does not help resolve the problem of CO2 emissions globally. With respect to the 2030 Agenda, this may be considered a temporary solution since to achieve the SDG goals, Vietnam will have to consider other sources of cleaner energy in order to align with the Sustainable Development Goals # 7 on affordable and clean energy.

Jan 1, 2017

By Yehia M. Eyssa

A "straight wire" flow through magnetic ore separator has been designed, built and successfully used to separate magnetite from typical slurries. The purpose of these experiments was to simulate the high field profile of a "straight wire" superconducting magnetic separator which would be capable of separating weakly magnetic hematite ore from typical slurries. Magnetite was used as the test mineral because it experinces the same magnetic forces at low field as does hematite at high field. The present separator concept is based on the fact that there is a particle concentration profile due to the gravity field for low velocity turbulent flow. When a magnetic field force of -g is applied the concentration profile of the magnetic particles will be reversed leaving the nonmagnetic particles flowing alone at the bottom of the channel. By means of a divider at the end of the channel the concentrate is separated from the tailings. It is shown that the time needed to deflect hematite particles in a narrow cylindrical channel concentric with the superconducting wire is small enough so that high throughputs in the turbulent flow region are possible. In the case of a high field superconducting separator the centrifugal force could replace gravity by rotating the flow around the straight wire conductor.

Jan 1, 1974

By Tyler Lahti, Peter Borgacci, Mary Jane Ferraro, Prakash Nadesparan

Toronto Tunnel Partners (TTP), under contract to Metrolinx/IO, is constructing new twin rail tunnels under the Highway 401 & 409 interchange to accommodate additional tracks to support the GO Expansion program for future two-way, all-day service. The new tunnels are being constructed using the Sequential Excavation Method (SEM) and utilize a tunnel pre-support system consisting of a series of 800 mm diameter steel pipes to form a pipe canopy. The pre-support pipes were installed with an Auger Boring Machine (ABM) in four separate headings; one heading from each of the tunnel end portals, and two from a shaft in the middle of the highway. To facilitate the auger boring operation, a custom steel reaction frame was required to counteract the thrust from the ABM at the portals, and a temporary shaft structure was installed in a narrow median space of the highway. The installation of the pipe canopy had to overcome challenges including removal of obstructions, alignment issues, and controlling settlements to the highway surface. This paper discusses the purpose of the pipe canopy, design and installation of the temporary shaft and structures to support the auger boring operation, the experience of the contractor during the installation of the pipes, and brief overview of the experience tunneling below the pipes.

Jun 13, 2021

By Gary Peach, Peter Mason

Planning and estimating progress rates and costs for tunnelling is always best done based on experience and historic precedent. Much precedent is available but the use of data monitoring, data mining and other retrieval techniques on modern TBM machines can enable this to be further expanded and refined. Advance rates can be related much more closely to rock types as can associated rock bolt and mesh/ shotcrete requirements. This in turn can lead to a further refinement in best likely combinations of equipment, such as shotcrete jumbos, better selected for the anticipated conditions, rather than the potential advance rates of the machine. Efficient and timely construction of the tunnel will also be linked to times needed for finishing work, such as contact and void grouting and to how this can be initiated while the TBM is still in operation, in order to save overall construction time. Indeed, this in turn may affect the most preferable layout and construction details of the permanent tunnel. Considerable experience has been gained in the use of two large diameter TBM tunnel drives through the Himalayas at the Neelum-Jhelum hydropower project in Pakistan. All the above aspects will be discussed in the paper based on the considerable experience and data which came from that operation, including appropriate measures in highly stressed areas potentially subject to rock burst.

Jun 13, 2021

By P. J. Mackey

A whole new group of non-ferrous pyrometallurgical processes with the ability to utilize tonnage oxygen and capture sulphur dioxide were developed and commercialized over the period 1940s–1980s. Many of these earlier process developments were undertaken with limited knowledge of the process chemistry and influence of key process variables; in many cases, piloting helped provide much new physico-chemical data, but gaps remained. The second generation versions of these technologies of today provide all the primary copper, nickel and lead produced worldwide by pyro-metallurgical smelting. Further, process development has continued and a new generation of copper and lead smelting technologies have also been developed in China since the 1990s. The older reverberatory and blast furnaces have been progressively replaced by the newer technologies—a good example being the introduction in 1992 of the copper IsaSmelt technology at the Mt. Isa smelter in Australia where the former fluid bed roaster and reverberatory furnaces were replaced by a single new smelting unit, together with an acid plant for sulphur dioxide collection. The development of these new technologies was made possible by investment in fundamental and applied research. The lesson for the future is, in order to sustain these improvements, continued investment in research and development capability is required—to do otherwise is to risk obsolescence and lack of competiveness in the world market. Dr. Peter Hayes at The University of Queensland is one of the many researchers and process engineers who have contributed to the fundamental understanding of metallurgical processes over this period of rapid change in technologies. The present paper briefly outlines some of the many contributions Peter Hayes has made to the understanding of kinetics, mechanisms and phase equilibria in metallurgical systems, and metallurgical process development.

By Xie Junjie, Li Shina, Ma Ruixin, Min Changli, Yin Zichen, Li Kang, Shi Zhuonan

Cesium and rubidium were effectively separated by zinc ferrocyanide coprecipitation method, and the effect of precipitant addition amount on the separation of cesium and rubidium was studied. Under the conditions of Zn/Cs molar ratio of 0.45 and Zn/Fe molar ratio of 1, the precipitation rate of cesium is 84.01% and the separation factor of Cs/Rb is 164.65. The thermogravimetric curves of the sediment were measured, and the effects of roasting temperature, roasting time, and leaching liquid/ solid ratio on the extraction of cesium were studied. Almost all of the cesium was extracted under optimal conditions: roasting temperature of 600 °C, roasting time of 3 h, leaching temperature of 25 °C, leaching time of 0.5 h, and liquid/solid ratio of 5:1 mL/g. After the leaching process, the leach liquor with high concentration of cesium of 80.17 g/L was obtained. Finally, the leach liquor was further purified by solvent extraction, and the purity of the cesium chloride product reached 99.66%.

Mar 17, 2024

By C. J. Webb

Abandoned uranium mines in the southern Black Hills of South Dakota were sampled for uranium, radium, and rare earth elements during 1992 and 1993. Analyses of water samples from several shallow ponds in the mine pits showed pH values between 3 and 4 with uranium concentrations between 1600 and 2600 ppb. Rare earth elements and their respective isotopes were analyzed with an inductively coupled plasma mass spectrometer and were referenced to a shale normalization pattern. All samples showed an enrichment in the middle rare earth elements. Rare earth levels often were greater than 0.2 ppm. At one site, the concentrations of lanthanides were 150,000 times above background levels. While the southern Black Hills have long been known for rich uranium ore deposits, these analyses show that significant levels of rare earth elements also are present, indicating that the potential exist for future development.

Jan 1, 1995

By Shiwei Wang, Ziwen Li, Chenhu Zhang, Peng Chen, Chengyong Wang

Accurate prediction of the partition coefficients in coal gravity separation is key to improving the preparation efficiency of coal and promoting its clean utilization. In China, the approximate formula method (AFM) has been applied to the calculation of coal gravity separation partition coefficients for decades, but its accuracy is limited. To improve the accuracy of the predicted partition coefficients, and thus the product yield of coal preparation plants, the present study proposes a modified hyperbolic tangent model to derive direct calculation formulas for the heavy medium and water medium separation partition coefficients. Four groups of coal samples were used to verify the accuracy of the direct formulas, and their predictions were compared with those of the AFM. The results showed that the partition coefficients and partition curves predicted by the direct formulas were closer to the actual values than those predicted by the AFM. Further, when the cleaned coal ash content was basically the same, the cleaned coal yield predicted by the direct formula was lower than that predicted by the AFM, and was also closer to the actual value. These results demonstrate that the direct formula produces more accurate results compared to the conventional AFM. As this formula has a reasonable theoretical basis, is simple to apply, and produces accurate results, it is expected to help improve the design and management level of coal preparation plants.

Oct 15, 2022

By Edward A. Nowatzki

The purpose of this paper is to present an example of the application of a theoretically derived mathematical model for track-soil interaction to the evaluation of the mobility of large-scale mining equipment used in open pit operations. The model described by Karafiath and Nowatzki (1978) and presented in detail by Karafiath (1978) was used to predict the performance characteristics of four different bucket wheel excavators (BWEs) on rwo types of copper mill tailings at various moisture conditions. The BWEs considered In the analyses are two-and three-tracked continuous excavators. Most have boom-mounted rotating buckets and swinging side- or rear-discharge conveyors. The analyses were performed at the request of Dames and Moore for the Kennecott Corporation's proposed remining of selected tailings deposits at the McGill, Nevada, concentrator. The objectives of the analyses were to determine whether BWEs would have sufficient mobility In the tailings deposit to achieve satisfactory production rates, and TO compare the predicted performance of the various BWEs evaluated. Good qualitative agreement was obtained between the results of the theoretical analyses performed for the McGil1 operation and the actual performance of BWEs in two South African gold mine tailings impoundments.

Jan 1, 1980

By V. Rajaram

The oil shales located in the Appalachian Basin cover an eight-state area of the eastern U. S., and are referred to as Devonian (black) shales. These shales have been exploited for their gas potential for several years. The Institute of Gas Technology (IGT) has conducted research since 1972 on the production of shale oil from the Devonian shales, and this resulted in the development of the HYTORT process. This process demonstrated that the yield from the Eastern oil shales can be greater than the value indicated by the Fischer assay method. IGT estimates that 423 billion barrels (67.3 x 109 m3) of oil could be recoverd by HYTORT processing of surface-minable eastern U. S. shales. Recently American Syncrude Corporation and Southern Pacific Petroleum N. L. have proposed oil shale projects in Kentucky. This paper will describe the surface mining and retorting techniques that have been studied for exploitation of the Devonian shales, and enumerate the problems that have to be overcome before commercial production can be realized from these shales.

Jan 1, 1983

By F. Wolf, R. Ellmies

"Fluorspar is one of the most important industrial minerals. It has a wide range of applications, for example it is used in the steel and aluminum industry, and is also the raw material to produce hydrofluoric acid, Teflon or Gore-Tex. There are only a few major fluorspar mines worldwide, with China being the most important fluorspar producer (U.S. Geological Survey National Minerals Information Center, 2017). At Okorusu, Namibia, fluorspar has been mined with conventional open pit mining methods from 1955 until 2014 from a large scale metasomatic fluorspar deposit with seven identified orebodies. There are about 7 million tons of measured resources left with an average grade of 27.5 % CaF2. This paper is based at an MSc thesis at Technical University Freiberg and describes the design of an underground mine for the A and D orebodies with an annual production rate of 100,000 t acid-grade fluorspar product. By comparing different mining methods and adapting variants of access to the underground orebodies the paper will emphasize on the selection of a suitable mining technology, with a special focus on the economic considerations to decide about the most profitable operation. INTRODUCTION Mining holds an important part in the economy of Namibia. In 2016 11.1 % of the GDP was made through mining activities with 22 active mines (The Chamber of Mines of Namibia, 2016). Only one of them consists an underground mining operation. The global annual production of fluorspar is approximately 6 to 7 million t (U.S. Geological Survey National Minerals Information Center, 2017). Okorusu produced on average about 50.000 t annually in recent years (U.S. Geological Survey National Minerals In-formation Center, 2015). Okorusu Mine is Namibia’s only fluorspar mine. Fluorspar was mined in an open pit mine with four individual pits (A-D) since 1980. In 2014 the mine closed due to the increased stripping ratio and beneficiation problems. The mine assets were bought by Gecko Namibia. Currently Gecko uses parts of the processing plant for beneficiation of graphite from a neighboring mine. Figure 1 shows a panoramic view with the four pits and the mine village. The intent is to develop a concept for the further underground development of the mine. There are still about 7 million t of measured resources left in the deposit, with an average grade of 27.5 % CaF2. This study focusses on the underground mine design. The above-ground plant and facilities are considered as remaining unchanged."

Jan 1, 2018