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By S. E. Phillipson

Underground mine mapping is a critical component of understanding the controls on ground instability. Many relatively localized examples of ground failure are associated with geologic features, such as faults, joints, compaction zones, or sedimentological transition zones. In contrast, long-running, directional roof falls are associated with regionally directed horizontal stress fields, which are induced by tectonic plate interactions in the earth?s crust. When stress-related features are distinguished from geological features, underground mapping can be an effective method for inferring the direction of horizontal stress at individual mines. Comparisons with data compiled in the World Stress Map confirm that underground mapping can be a valid method for determining the orientation of maximum principal horizontal stress at a variety of scales, ranging from individual mines to an entire mining district or coal basin. Comparisons are presented between the maximum horizontal stress directions inferred by MSHA?s Roof Control Division through underground mapping and the azimuths of maximum horizontal stress in the World Stress Map database for North America?s Pennsylvanian-aged Appalachian, Illinois, Black Warrior, and Arkoma Basin coal fields. The comparison indicates that azimuths are similar for both data sets, even where variations in the direction of horizontal stress are present. It is interpreted that inconsistencies in direction are attributable to near-surface affects such as deeply incised stream valleys, or to fault zones that represent heterogeneities in the crust.

Jan 1, 2009

By Sunil Koppalkar, Guillaume Noel, Ahmed Bouajila, Makni Sami, Claude Gagnon

"Gold gravity recovery circuits utilizing enhanced gravity separators have become an integral part of many of the modern gold processing plants. Thus, efforts to improve the operating efficiency have been a topic of interest for metallurgists for many years. As part of this endeavour, a methodology to estimate the portion of gold in the ore that could be recovered by gravity separation (gravity recoverable gold or GRG) was developed at McGill University. It has been reported in the literature that the gold content estimated with this methodology is the theoretical maximum that is available for gravity recovery that could only be approached but never achieved. A comparison of GRG recovery obtained in the laboratory with the actual recovery in the plant shows that plants recover between one-third to two-thirds of the value predicted by the laboratory test.Research conducted at COREM shows that particle shape transformation during grinding is a major cause of the discrepancy (even though the bleed percent processed, the quality of cyclone classification and the operating conditions of the gravity separator also contribute to the difference). To analyze the gold particle shapes and their deportment, samples were collected from different streams of a grinding-gravity circuit in a gold plant and compared to a concentrate sample from the standard GRG test. A particle characterization methodology based on gold morphology was developed. GRG mapping in a conventional grinding-gravity circuit and the transformation of GRG into non-GRG, as mainly explained by gold particle reshaping, will be discussed. The knowledge gained from the shape analysis will be used to develop shape distributions and partition curves for the classification of shapes.INTRODUCTIONGravity concentration using centrifugal concentrators has gained increasing popularity since the invention of the enhanced gravity concentrators in the nineteen eighties. Among these, the semicontinuous centrifugal gravity concentrators are most commonly used for recovering gold and platinum group minerals (PGM) from grinding circuit streams. The benefits of gold gravity recovery are now well understood and the acceptance by the mining industry is overwhelming. The occurrence of reasonable amounts of gravity recoverable gold (GRG) in an ore prompts gold mills to install gravity circuits. Thus, the increased use of gravity concentration has necessitated a better understanding of the behavior of gold in grinding circuits and of the factors affecting the performance of the gravity concentrator (Laplante et al., 1995). Due to its high density (19.3 g/cm3 when pure) and malleability properties, gold tends to accumulate in circulating streams making it attractive for gravity recovery. The gravity recovery units are typically installed on a bleed stream of the cyclone underflow, mill discharge or cyclone feed."

Jan 1, 2011

By Dapeng Zhang, Brij Moudgil, Shibo Zheng, Chunhui Feng, Wenyi Song, Wending Xiao, Patrick Zhang

Separation of dolomite from phosphate is the most challenging problem in phosphate mineral processing. Over 50% of the future phosphate reserve in Florida contains too much dolomite to process using the current industry practice. The current phosphoric acid production practice requires less than 1% MgO in the phosphate concentrate as the feed material. The Florida Industrial and Phosphate (FIPR) Institute has collaborated with worldwide experts in the field to address this issue. As a result, the industry is now offered three feasible options. Option 1 offers three methods for reducing MgO content in the concentrate from the Crago process, including adding a dolomite depressant in the rougher flotation step, dolomite flotation of the cleaner concentrate, and scrubbing the cleaner concentrate in quartz sand. These methods could reduce MgO content in the final concentrate by 20–40%. Option 2 involves crushing and grinding of high-dolomite phosphate pebbles followed by dolomite flotation at slightly acidic pH using a new collector that does not require phosphoric acid as a phosphate depressant, achieving a final concentrate analyzing less than 0.9% MgO at about 87% P2O5 recovery. Option 3 is a gravity separation technique using an innovative separation jig, and its full potential remains to be demonstrated.

By G. F. Livingston, F. K. Shelton, J. C. Stahl, R. E. Churchward

"INTRODUCTION An investigation of the metallurgy of cobalt from domestic ores has been in progress since February 1940 and has resulted in the formation of a hydrometallurgleal process for the production of electrolytic cobalt metal. Previous reports of these investigations have been given by F. K. Shelton; 7/ and Ruth E. Churchwrd, F. K. Shelton, and G. Knickerbocker. 8/ Briefly, the process, as applied to ores containing cobalt oxide, consists of leaching with H2SO3 or, preferably, with H2SO3 and H2SO4, to dissolve the cobalt. The cobalt solution passes through one or more purification stages to remove iron and elements of the copper group, and cobalt carbonate is precipitated under carefully controlled pH conditions. The cobalt carbonate is dissolved in on acid electrolyte containing sulfuric acid, boric acid, and sodium fluoride. The electrolyte then proceeds to electrolytic cells where cobalt is plated as a metal and sulfuric acid is regenerated.The present paper contains the results of several investigations signed to give a more complete chemical and engineering understanding of different unit processes involved in the electrowinning of colbat. Some work has been done to broaden the process to include arseniferrous cobalt ores as well as the oxide ores upon which the investigation was initiated. Most of the data presented herein have been obtained since the release of the previous reports; any changes suggested heroin that conflict with recommendations in earlier reports are based on more complete data and usually are preferable."

Nov 1, 1945

Suggestions have been made at various times that there may be a recurrence of lodes similar to those at Kalgoorlie in the country to the south of the Golden Mile, but, so far as is known, there has been no geological evidence to support these suggestions apart from the possible extension of the younger quartz-dolerite greenstone in this direction.Geological mapping carried out by the writer in the Coolgardie district in 1946, provided some additional geological evidence to support this claim, and the ideas then held have since been expanded and are now considered to be sufficiently advanced to present them as concrete suggestions. As will be seen from the following pages, the critical area for lode prospecting is Hannan's Lake, where the basement rocks may include younger quartz dolerite greenstone, which, although perhaps distributed over a smaller area than at Kalgoorlie, could, on structural grounds, have a similar fracture system and similar ore deposition.There is little need to stress the importance discoveries in this area would have in prolonging the life of the field, and stimulating the post-war gold mining revival.Previous Work: Only the publications having a direct bearing on the preparation of this paper are given in the list of selected references, but the writer is very conscious of the fact that much other geological work has been carried out in the Kalgoorlie district since its discovery, by the W.A. Department of Mines, by mining companies, and others, all of which has contributed to the present knowledge of the field, and acknowledgment of the value of this work is given herewith. In presenting the suggestions in this paper a broad structural control of ore deposition is assumed, but this has already been established in other parts of the goldfields of Western Australia, including adjacent areas. In the early nineteen thirties, the Western Mining Corporation commenced work on the basis that there was a close relationship between geological structure and auriferous ore deposition, and a similar approach was first made by the Geological Survey of Western Australia in the South Yilgarn in 1935. These ideas were further developed during later surveys, particularly in the North Yilgarn and the Mount Margaret Goldfield.During the Coolgardie Survey in 1946, broad structural mapping was done in greater detail than before, and the structural ideas were implemented and further developed, leading to some success.Other work to which particular acknowledgment is given is that of Stiltwell, Gustafson and Miller, Forman, Prider and Finucane, at Kalgoorlie, and that of Honman in the Kalgoorlie-Coolgardie district, references to which are given at the end of this paper.Valuable constructive criticism of this paper has been given by Professor E. de C. Clarke and Dr. R. T. Prider, of the University of Western Australia.

Jan 1, 1950

By Wawa Jaka Sungkawa, Slamet Rachman Jaka, Tom Dermody

Nowadays, with such a focus on environmental protection, surface mining activities have come under pressure to ensure their activities do not adversely affect the local surroundings. As part of the extractive process, blasting activities are an integral part of a mining company’s operational cycle. Consequently achieving beneficial blast results while complying with environmental requirements has become a key focus. This especially is the case when firing blasts within close proximity of residents where additional control measures need to be implemented to control vibration. One case where this occurs in Indonesia is in the Paringin Pit, one of the operational areas of the company's. The pit has complex geological conditions and is surrounded by several residential areas. Between 2014 to 2017 there were 12 cases of ground vibration exceedance due to blasting. As part of a continuous improvement project the company's targeted minimizing the vibration exceedance in this area. A project was undertaken to research and develop a method to confidently predict vibration. It was decided that the scaled distance formulas were not adequate to predict vibration when using non-electric detonators, as accurate wave propagation could not be achieved. The problem is how to manage of complex geology condition related with wave propagation in ground vibration control. Geological condition mapping with specific spatial range can and combine with Signature Hole Analysis be a solution to make wave propagation easier to accommodate in ground vibration control. With this new approach geological condition mapping with specific spatial range was produced that would minimize vibration while ensuring beneficial blast results. Introducing the new prediction produced nil cases of vibration exceedance in 2018 and beyond and proved that the Signature Hole Analysis in specific spatial range of geological condition is the preferred method to optimize blast result and maintain vibration control.

By S. K. Singh

To meet increasing demand of coal, underground mining is largely being replaced by the exploitation at deeper horizons and with greater complexities. The exploitation-proposition may be below not-to-be-disturbed surface properties or below water-bodies, posing a constant threat of inundation. Also, the mounting pressures to limit the adverse impacts on the environment bring the extraction-undertaking to face more challenges. An understanding of subsidence-mechanism and a rational quantification of subsidence parameters is a requisite herein. This paper presents such pragmatic quantification, validated at mine-sites in India. In comparison, better productivity, conservation and safety is ensured in this approach.

Jan 1, 1999

By James M. Baugher, Donald W. Conrad, William J. Wiehagen

This report describes a process for quickly developing information that is useful for skills training. The process is called job training analysis (JTA). Its main use is to structure skills training at the jobsite. JTA supports structured skills training by identifying the job duties, tasks, and steps and the reasons why those job components are important. The outcome of the JTA process is a worksheet—a training outline based on the knowledge and expertise of experienced workers. Time invested in developing a JTA will result in significantly more time saved when it is used appropriately by skilled trainers. Like a roadmap, JTA saves time and energy. Experimental work at several mine sites helped document, refine, and validate the JTA process. JTAs for two mining jobs—roof bolting and lift truck operation—at two different mine sites are used to illustrate some of the concepts and the specific JTA process described in this report. The work at these two sites was influenced by cooperative work between the Mine Safety and Health Administration (MSHA) and the National Institute for Occupational Safety and Health (NIOSH) at several other mine sites and prior collaborative work with the U.S. Navy. The mining JTA process is grounded within the military research on the design of instructional systems. MSHA and NIOSH worked to simplify and apply the military training development model for mining industry use through collaborative work at several mine sites. The JTA process involves three activities: (1) planning, (2) a 1- to 3-day workshop where the JTA is developed using facilitated work with subject-matter experts, and (3) followup. Guidelines and considerations for each of these activities are included. Results indicate that the JTA process has been well received and valued by mining industry participants. It blends aspects of health and safety, production, maintenance, and crew coordination.

Jan 8, 2006

By Mark K. Larson

Calibration of LaModel for deep coal mines begins with adjustment of overburden stiffness for load transfer distance. This calibration determines whether mining induced stresses are concentrated in the immediate abutment of the gob, or spread over a wider area. In the absence of site information, an empirically-based estimate is often used. Where data is available, a recommended calibration procedure can be followed, as is done in this case study at a deep western longwall mine, with minor modifications and extensions. In this case, data sources included borehole pressure cells, flatjacks installed in series with support Cans, and observed changes in ground conditions. Calibration was based on the first detection of mining-induced stress from the advancing longwall. Detection was found to depend on the type and sensitivity of measurement. Borehole pressure cell data with a 20-psi-increase detection threshold were chosen as the standard, in accord with data used in deriving empirical relationships. Application of this standard produced a load transfer distance estimate roughly four times the empirical relationship developed by Peng and Chiang (1984). This is a significant deviation with important implications for panel design at this site. Data from flatjacks, ground condition observations, and borehole pressure cells with higher threshold values, were tightly clustered and show load transfer distances from two to four times empirical guidance. Ratios between various measurements can be used to adjust measurements to the standard (although they may depend on mine geology). Once established, ratios can be used to adjust estimates, say from support flatjacks or ground observations, to the standard, where borehole pressure cell data is not available.`

Jan 1, 2012

By Conochie D. S, Grave N. C

Disposable-tip emf cells at present used in liquid steel can be used to measure the state of oxidation of high-iron slags produced in non-ferrous smelting. This provides a new tool for the control and evaluation of pyrometallurgical operations.An investigation of oxygen potential variations throughout a typical nickel smelter using the flash smelting technique gave a valuable insight into the process. Correlations of oxygen potential with ferric to ferrous oxide ratio and nickel content in slag were in reasonable accord with equilibrium data in the literature indicating that the probes may be used both as a plant investigation tool and possibly as a means of obtaining thermodynamic data for slags.

Jan 1, 1979

By Herman W. Hill

This report summarizes research into the root causes of failures in mine power systems which impact safety and reliability. Abnormally low fault currents, due to arcing faults, self-excited systems, and fallen trolley wires are examined and quantified. The reliability of components which are critical for safety is studied, as well as reliability of components which are crucial to the mining pro cess. Failure rates are found through in-situ tests, accelerated life tests, studies of mine maintenance, and fault-tree analysis. Reliability data is used to predict fatalities and lost-time accidents through computer-aided fault-tree analysis. Analytical support tasks reported include the deriving of trailing-cable ampacities under cyclic loading, and the measurement of connected ground beds.

Jan 1, 1981

By Rudolph P. Frizzi

Quality control is essential for augered cast-in-place (ACIP) piles (also known as continuous flight auger (CFA) piles outside the United States) and drilled displacement (DD) piles since the pile is constructed below the ground surface out of the direct sight of the personnel constructing and inspecting the pile. ACIP piles are being successfully constructed to support high-rise structures, hospitals, arenas and stadiums, mass transit systems, and power and industrial facilities. The use of DD pile technology is also gaining ground in the United States, typically utilizing proprietary systems such as Omega (currently utilized by Richard Goettle Inc., and LG Barcus and Sons, Inc.), Berkel, and DeWal (currently utilized by Morris-Shea). Different types of ACIP/DD pile installation equipment are shown in Figures 1 and 2. ACIP piles are installed into granular and cohesive soils, and soft rock to lengths currently approaching 130 ft (39.5 m), with diameters up to 24 to 36 inches (610 to 915 mm), and sustaining design loads approaching 900 kips (4000 kN). Current DD pile installation equipment in the United States is capable of installing up to 79-ft-long (24 m) piles with diameters ranging from 12 to 18 inches (305 mm to 460 mm).

Jan 1, 2004

By Carlos Soria

El presente texto describe los Sistemas de Gerencia de la Información y su aplicación en la industria minera con el objetivo de optimizar la gestión total de la empresa. Dichos sistemas manejan información del proceso y sus valores de producción, cálculos, consumos de energia, emisiones de plantas, tiempos de funcionamiento de equipos, eventos, alarmas, mediciones de laboratorio y control estadístico, etc. De forma que dicha información pueda ser reunida y consolidada, convirtiéndose en materia de significado y relevancia disponible en base a análisis, reportes, listas, tendencias y gráficos para que el usuario final de una planta o en sus oficina pueda tomar mejores decisiones.

Jul 17, 2000

By Beevers J

The Ok Tedi Project is now a high production open-pit porphyry copper mine located in the Star Mountains of Papua New Guinea (PNG). At present, total daily production is 190 000t of ore and waste. Large scale drilling and blasting has only been in operation since 1988, prior to which all material was removed by ripping and dozing. This paper reviews the steps taken over the last 12 months in establishing a more efficient drilling and blasting operation and highlights the significant reduction in powder factor. These improvements have been achieved largely through the introduction of air-bags, controlled pattern expansion and an overall focusing on the operation by involving consultants, ICI's technical service and internal departments.

Jan 1, 1991

Radioisotope x-ray methods for the on-stream determination of copper, lead, and zinc in mineral product slurries were developed, and were successfully tested at the plant of Cobar Mines Pty. Ltd.The tests were made in three stages. Measurements to determine the precision of analysis were made initially on briquettes of the mineral products. The effect of slurry solids content variations was then determined by measurements on the mineral products in a recirculating slurry loop. The radioisotope analyser was finally tested in a series of on-stream measurements in the plant.Copper, lead, and zinc in flotation feed and in copper concentrate were determined to a precision ranging between 1·4 and 15 per cent of the mean element concentration in the slurry solids. These precisions are within limits required for plant control purposes at Cobar.

Jan 1, 1971

In February 2001, Kalgoorlie Consolidated Gold Mines (KCGM) commissioned its first full-scale ultra fine grinding (UFG) plant to supplement existing roaster concentrate treatment capacity. This process involves the fine grinding of refractory pyritic concentrate to 10µm, followed by direct cyanide leaching for the recovery of gold. By this means gold is economically extracted from the concentrate without the need to first oxidise the host pyrite. This paper details the history of the project from initial laboratory testwork comparing possible treatment options, to current performance of the 12 tph plant. This includes the cost comparison of the major treatment options, the laboratory and pilot scale UFG performance, the UFG mill selection, cyanide leaching of UFG product, commissioning and plant performance to date.

Jan 1, 2002

By Barrick Pierina, John Frostiak, Igor Gonzales, Kenneth G. Thomas, Ken Manning

"1.0 SummaryThe Pierina deposit was acquired in August 1996 when Barrick Gold Corporation purchased Arequipa Resources, a junior mining company with extensive land positions in Peru. At the time of acquisition, Arequipa had developed two exploration tunnels and drilled 9 exploration holes on the property. Metallurgical tests, conducted on samples taken from the tunnels and the exploration holes indicated that the ore was amenable to heap leaching. Barrick’s exploration team recognised from the outset, the potential of the mineralisation and convinced Barrick’s senior management that this was indeed a world class deposit that should be pursued. On November 25, 1998, the first dore was poured at Pierina, 27 months from the time of acquisition. During that period Barrick completed its exploration programme, prepared a development plan including capital and operating costs, production profiles and cash flow forecasts, and a schedule to develop a mine and construct a leach pad and gold recovery plant, including all supporting infrastructure. All permits and environmental approvals were obtained and all necessary land was acquired. The project was completed on schedule and under budget. This was the first greenfield mine development for Barrick outside of North America.This paper details, mainly, the research and development, engineering, construction and commissioning of the metallurgical process facilities.2.0 The Develonment ProgrammeImmediately after the acquisition, Barrick began the process of gathering information required to prepare a project development plan. Kilborn Engineering was retained to assemble all of the information collected and collated into a development plan document. This document was completed by June 16,1997. The objective was to bring the mine into production as quickly as possible with critical activities identified as follows:"

Jan 1, 2000

At Great Boulder Gold Mines Ltd. a number of attempts were made to remove water soluble copper and iron salts from calcined pyritic concentrates but variou~ problems arose and the methods were abandoned.A method of rapid washing has been developed and although some problems still exist a workable process was established which resulted in substantial savings of reagents used for the cyanidation of calcine.INTRODUCTIONIn the Great Boulder flowsheet crude ore is ground in cyanide solution, then thickened, agitated and subjected to two stage filtering. Secondary filter discharge is pulped with flotation circuit water, gassed with sulphur dioxide to precipitate soluble gold and activate pyrite, and after the addition of copper sulphate and xanthate, the pyrite and tellurides are recovered by flotation. Flotation tailings are thickened and pumped to the disposal area and concentrates are calcined in Edwards roasters. Calcine is washed to remove water soluble copper and iron salts and the washings pumped to the flotation section where the copper is used as an activator. The washed calcine is cyanided and returned to the crude ore circuit via the thickeners. Solution for precipitation in the Merrill Crowe is drawn from the crude ore thickeners.Prior to the introduction of calcine washing the calcine contained 7 lb/ton copper of which approximately 60 per cent was water soluble. It also contained approximately 90 lb/tol'l of water soluble iron salts. Both the copper and...

Jan 1, 1964

By Richard J. Finno

Detailed measurements made at a test section adjacent to a deep braced cut and other published data are combined to illustrate the limitations of the common methods of predicting movements associated with excavations in soft to medium clay. While past performance data can be used to estimate expected responses before construction in many cases, actual wall and soil deformations throughout construction can only be estimated using finite element procedures. Success of such analyses depends equally upon considering all aspects of construction that induce strains in adjacent soil, such as wall installation, excavation and bracing sequence, and time, and adequately modeling soil stress-strain behavior. Even when these two criteria are met, soil deformations can not be predicted adequately when strain levels exceed those that produce peak shear stress.

Jan 1, 1991

By Weng Fu, James Vaughan, Stefan Lakemond

Uranium bearing copper sulphide flotation concentrates produced from iron oxide copper gold uranium (IOCG–U) ore contains radionuclides such as 238U, 230Th, 210Pb, 226Ra, 210Po, which have the potential to reduce their marketability, thus posing a challenge to the industry. Thus, a two–stage leach process has been proposed in this study. In first stage, a sulphuric acid leach process effectively dissolve most of the 238U and 230Th into solution, but other radionulclides (mainly 210Pb, 226Ra and 210Po) remain associated with copper sulphide minerals owing to their low solubilities in sulphuric acid solution. In the second leaching stage, the use of methanesulfonic acid (MSA, CH3SO3H) is investigated to selectively dissolve the 210Pb, 226Ra and 210Po from the residue of the first stage. The results indicate that 96% of 238U, 87% of 230Th, 90% of 210Pb, 86% of 226Ra and 17% of 210Po are dissolved using 3 mol/L MSA solution at 90°C for 3 hours, which represents a dramatic decrease in the radioactivity of the copper concentrate. INTRODUCTION Australia is host to one of the largest iron oxide copper–gold–uranium (IOCG–U) deposits in the world. Most of the value in these deposits is associated with copper. In mineral processing, the gangue minerals are separated from copper sulphide minerals that report to a copper flotation concentrate. However, due to the strong association of uranium with copper minerals and hematite, even clean copper concentrates can contain significant amounts of uranium (238U) and its radioactive decay elements, of which thorium (230Th), radium (226Ra), lead (210Pb), and polonium (210Po) are the long life radionuclides. These hazardous radionuclides negatively affect the marketability of the copper concentrates. Customer copper smelters in China, Japan and Europe may consider the radionuclides penalty elements or may not be able to process the feed. Therefore, there is a strong motivation to remove radionuclides from copper concentrates at the mine site before shipping to custom smelters in global market. Hydrometallurgical leaching has been widely employed to remove radionuclides from different kinds of minerals such as copper concentrates (Ragozzini & Sparrow, 1987), zircon concentrates (Aral, Sparrow, McDonald, & Norgate, 2007), and coal ash (Lei, Qi, Sun, Xu, & Wang, 2014). Leaching using sulphuric acid (H2SO4) solutions is the most widely used process for the extraction of uranium from uranium ores due to the relatively low cost and wide availability of the acid (Bhargava et al., 2015; Gilligan & Nikoloski, 2015). The leach process involves treating ground ore slurry with sulphuric acid at elevated temperatures (typically 60–90 °C) under oxidising conditions in order to convert the uranium in the minerals 2+ from the relatively insoluble tetravalent form (UO2) into water–soluble hexavalent state (UO2), which then complexes with SO42- and forms UO2(SO4)22- in solution. The uranium oxidation is generally carried out in the presence of ferric ion (Fe3+), regardless of the reagent and oxidant used. The most commonly used oxidants for uranium include sodium chlorate, pyrolusite and oxygen (Ring, 1980). These oxidants act indirectly by converting ferrous sulphate, formed by the oxidation reaction of UO2 in slurries, into ferric sulphate. The presence of Fe–containing gangue minerals such as hematite in the ore usually provides sufficient Fe required for the oxidation of UO2. After sulphuric acid leaching, the locked thorium (230Th), radium (226Ra), lead (210Pb), and polonium (210Po) elements are chemically liberated from hematite and uranium mineral grains (Ciobanu, Wade, Cook, Schmidt Mumm, & Giles, 2013). However, the extraction rate of radium (226Ra), lead (210Pb), and polonium (210Po) in sulphate solution is very low due to the limited solubilities of (Ra, Pb, Po)SO4 (Bagnall & Freeman, 1956; Liu & Papangelakis, 2006; Nikitin & Tolmachev, 1933).

Jan 1, 2019