Search Documents

By J. A. Batista-Rodríguez, F. J. López-Saucedo

A new methodology is proposed for the preliminary assessment of coal blend quality, which combines gamma-ray spectrometry and magnetic susceptibility measurements. This methodology does not replacethe conventional methods of assessing coal quality, but can help to control the quality of the coal blending process, as well as reduce the amount of proximate analysis required and the determinations of calorific value and total sulphur. The methodology includes five steps. First, both geophysical measurements aremade with handheld equipment. The samples with magnetic susceptibility ≤ 1 × 10-3 SI are then separated. From these samples, those with total gamma intensity ≤ 20 nGy/h are separated. These samples have a higher calorific value and lower ash and moisture content. To separate the samples of better quality and with lower total sulphur content, in step four the samples with total gamma intensity > 20 nGy/h are separated from those with magnetic susceptibility ≤ 1 × 10-3 SI. This last group includes samplesthat will cause less total sulphur-related environmental pollution. In the final step, the quality of both radioactive sample groups is corroborated from the calorific value measurement and ash, moisture, andtotal sulphur contents in at least 10% of all coal blend samples from both groups. In this study, more than1000 samples were analysed with this new methodology, and the results are remarkably similar to the ASTM classification of the Sabinas Basin coals.

Apr 2, 2022

By A. Pareek, V. S. Masampally, V. Runkana

Mineral processing plants, in general, consist of comminution and separation circuits. Rougher flotation is considered as the heart of the separation circuit with concentrate grade and mineral recovery being the key productivity and quality parameters that affect the downstream operations and profitability. Online prediction of these parameters can help improve process performance in real-time. Past efforts to predict flotation cell performance have focused on building physics-based or machinelearning (ML) based models. Although physics-based models are popular in process design applications, ML models are more appropriate for online monitoring, control and optimisation due to their lower computational requirements. Deep learning (DL) is gaining prominence nowadays for application in industrial operations where a large amount of data is available. We have developed a DL model based on long short-term memory (LSTM) neural networks to forecast the two key performance indicators (KPIs), namely, mineral recovery and concentrate grade in a mineral processing plant. Rougher feed characteristics such as mineral grade and particle size distribution, upstream measurable disturbances such as throughput of the comminution circuit and pulp density, and control variables such as aeration rate, pH, and collector addition rate are considered as explanatory variables to train the model. The model was tested with data from an industrial mineral processing plant. For real-time dynamic predictions, the trained model appropriately accounts for mismatch in measurement frequency of real-time process data and off-line laboratory analysis data. Such a time series model can be used as a state observer in model predictive control techniques for optimal control of unit operations in a mineral processing plant. Keywords: Mineral processing, flotation, time-series, dynamic modelling, deep learning

Jan 1, 2020

By I. O. Flores, A. Anani, H. Li

Current technological advancement has increased the exploitation of deeper ore bodies using underground methods. In certain cases, the mineral deposit starts near the surface and continues deep within the earth's crust. Such deposits are best mined with both underground and surface methods. Two main techniques are used to determine the optimal transition depth from surface to underground - a disintegrated approach and an integrated approach. Both methods have limitations in their use to determine the optimal transition depth. The objective of this research is to investigate the conditions in which an integrated approach to the transition depth problem is superior to a disintegrated approach. Three binary integer linear programming models are developed for this purpose: a surface and underground model for the disintegrated instance and an integrated model. A case study is performed to validate the models, with a comparative sensitivity analysis to obtain operational insights.

Sep 1, 2021

By A. Yañez, J. Yianatos, P. Vallejos, R. Grau

This paper presents an evaluation of the effect that the mineral feed characteristics have on the metallurgical performance in an industrial flotation circuit. Variables such as mineralogy, particle size, solid content and mineral grade were evaluated using a flotation simulator, which was previously developed and validated using industrial data from different concentrators. The metallurgical performance was evaluated not only from the point of view of recovery and concentrate grade, but also by analysing less common variables such as froth carrying rate, froth and collection recovery, water recovery and others. Then, new data from the industrial flotation circuit was used to complement this analysis and evaluate the simulator predictability by comparing simulated and measured data. The results allowed for the quantification of the significant effect that mineralogy and particle size have on recovery and/or concentrate grade. Therefore, the grinding stage and flotation cells design become important factors to avoid a significant loss in metallurgical performance when feed mineral characteristics change in an industrial operation. In this context, an evaluation of cells design and arrangement should be performed to compensate the loss in recovery and concentrate grade in order to find an optimal operating condition. Keywords: Flotation circuits, mineral feed, modelling, particle size, liberation, mineralogy

Jan 1, 2020

By Xiang-nan Zhu, Hao Zhang, Lin Li, Jun Qiu, Yue-xian Yu, Chun-chen Nie, Xian-jun Lyua

Waste printed circuit boards (WPCBs) are excellent metal resources. Mineralogical characteristics of different components in WPCBs were analysed in this study. Organic-enriched particles, fibreglass-enriched particles, associated particles and metal-enriched particles were obtained by density gradient method. Subsequently, the elemental composition, morphology, dissociation characteristics, functional group composition and phase composition of different components were analysed by X-ray fluorescence spectrometer (XRF), scanning electron microscopy and energy dispersive spectrometer (SEM+EDS), infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Elemental analysis results show that Cu is mainly contained in metal-enriched particles. SEM+EDS analysis results demonstrate that ideal dissociation can be achieved when the WPCBs are broken to -1 mm. Organic matter particles are enriched with carbon and oxygen elements, while fibreglass particles and associated particles mainly contain Al and Si elements, verified by XRD analysis. FT-IR results show that hydrophilic and hydrophobic groups exist widely in all components, caused by widespread organic matter. This study reveals the important properties of different components in WPCBs, which is of great significance for the subsequent separation process. Key words: Waste printed circuit boards, mineralogical analysis, elemental composition, dissociation; phase analysis, functional group composition

Jan 1, 2020

By B. P. Watson, A. Carpede, W. O. Kekana, N. Fernandes, W. Theron, M. P. Mahlangu, G. Betz

The research described in this paper was done to confirm the Upper Group 2 (UG2) PlatMine peak pillar strength formula (Watson et al., 2007), which was determined from a back-analysis of failed and unfailed pillars. Underground measurements were made on a stable pillar that was loaded by firstly reducing it’s length and then by mining the surrounding pillars until pillar failure took place. The pillar was instrumented with suitably positioned strain cells and closure meters, which allowed both the average pillar stress and strain to be determined. The paper describes the methodology applied to identify a suitable position for the instrumentation, as well as the results. A stress/strain curve is presented for a UG2 pillar with a w/h ratio of 2.0, at Booysendal Platinum Mine. The measured pillar strength was similar to the predicted strength using the PlatMine pillar strength formula for UG2 pillars. The PlatMine formula has been successfully implemented on Booysendal Platinum Mine, and about 3 670 pillars have been cut without a single failure. An additional revenue of US$1.3 billion was calculated for the 25-year life of the mine as a direct result of the improved pillar design, given the January 2020 platinum group metals basket price. An extended life of mine and better mining efficiencies will also be realized.

Aug 1, 2021

By R. A. Wildenboer, R. F. Sandenbergh

Rare earth elements (REE) are present at concentrations of approximately 0.36 % in phosphogypsum stacks located in Phalaborwa, South Africa. The REE are present in the phosphogypsum in solid solution in the gypsum and as fluorine and aluminium rich precipitates. Recovery of the REE offers opportunities for valorization and reducing the environmental impact of the phosphogypsum waste. This paper presents the results of investigations into the leaching behaviour of rare earth elements and other impurities from phosphogypsum using aqueous sulfuric acid. The effects of acid concentration, temperature, residence time, and the influence of impurities were evaluated for their impact on the solubility of rare earth elements in a sulfate medium. It was found that a significant fraction of the REE can be leached from the phosphogypsum in a range of conditions much less severe than traditional hard rock rare earth processing conditions. The REE were leached at a sulfuric acid concentration of 110 g/l, temperature of 30°C – 40°C and a residence time of approximately 8 hours.

Nov 6, 2024

By P. J. Le Roux

"Mining companies are under constant pressure to reduce their cost structures to sustain profitability. In mines using an open stoping mining method, dilution often has a significant effect on profitability. At Target mine in South Africa, dilution in some open stopes was found to exceed 10%, falls of ground being a major contributor to the problem. This dilution can reduce the recovered grade from 5.5 to 4.5 g/t, resulting in a potential loss of about R21 million per month based on a gold price of R240 000 per kilogram. In addition to the cost of dilution, the cost of damage to, or loss of, trackless equipment as a direct result of falls of ground in open stopes is significant. Other associated costs include transport, hoisting, secondary blasting, milling, and plant treatment of waste material. Stable open stopes are essential in order to reduce falls of ground. Back-analyses of stope instability at Target mine have indicated that conventional rock mass failure criteria are unsuitable for stope design. An alternative strain-based criterion has been developed, and has proved to be very successful, allowing the stability of open stopes to be calculated reliably. Since its implementation in 2010, dilution and equipment damage have decreased markedly, creating value for the mine. IntroductionMines that make use of an open stoping mining method aim to extract only the ore, leaving the waste behind. Many orebodies have well-defined boundaries between the ore and the waste rock. In such orebodies, the introduction of waste into the ore due to overbreak dilutes the grade. In massive disseminated orebodies, dilution is less problematic. Overblasting, falls of ground, or other causes may result in dilution. A study undertaken in Canada (Pakalnis et al., 1995) found that approximately 51% of all underground metal mines utilized open stoping mining methods and, from surveys conducted at these mines, open stoping operations experienced dilutions of up to 20%, and occasionally more. Dilution of this magnitude has a significant economic impact on any mining venture. Research carried out in Australia by Capes (2009) came to the same conclusion."

Jan 1, 2017

By W. Wilmans

Electrokinetic dewatering of kimberlite slime under constant direct curents of 0,5 to 2 A and dewatering under constant applied potentia Is of 16,5 to 46,5 V are considered. The combined efects of electrophoresis and the addition of 8,3 x 10-3 M Mg2+ ions on the one hand, and 1 to 10 p.p.m. of the anionic polyacrylamide flocculant Praestol 2935 on the other, were investigated in a 3-litre Perspex electrophoretic cel. .The electro-osmotic dewatering experiments were conducted in a 3-litre Perspex electro-osmotic cel at various electrode spacings, as well as with a moving anode (top electrode). During electrophoretic dewatering, the zeta potential of the kimberlite particles did not change significantly, whereas the pH and temperature showed marked increases with time. The addition of Praestol 2935 enhanced the setling of the sludge bed owing to the additional effect of flocculation. The addition of electrolyte Mg (CIO4)2 retarded the separation process, partly as a result of gel formation in the slurry. During the electro-osmotic experiments, the rate of dewatering was found to be approximately proportional to the applied constant direct current, and to be independent of the electrode spacing. In general, electro-osmotic dewatering seemed to be more energy-efficient than electrophoretic dewatering.

Jan 1, 1987

By J. Labuschagne

The primary factor contributing to the profitability of a platinum mine and its associated concentrator is the time taken from the first hoist of material from underground to the first batch of concentrate shipped. To minimize the time it would take to produce concentrate without stopping because of a lack of feed material a project was undertaken to integrate the mining model with a concentrator production schedule () in the most capital-effective manner. A secondary goal was to ensure detailed stockpiling requirements, as the concentrator is in an area where ?visual pollution? is to be avoided. To achieve this a dynamic stockpile model was created utilizing the mine production schedule resolved into a daily production figure. Four different concentrator development models were then proposed. The difference between the mine production and concentrator consumption was integrated over the life of the mine to provide the accumulated stockpile tonnages for both Merensky and UG2 ores. The stockpile levels were never allowed to fall below zero to prevent a situation where the concentrator was operational without feed material,. When a development option was selected, the standard metallurgical performance calculations were used to derive a concentrate production schedule, that was then used as a basis for commercial concentrate sale negotiations.

Jan 1, 2012

By K. -I. Higuchi, M. Mizutani, K. Haga, A. Shibayama, A. Batnasan

In recent years, the quality of iron ores has decreased due to the increase in the content of impurities, namely quartz, aluminum, phosphorus, and sulfur. It indicates that the removal of impurities from iron ore is an extremely challenging task. In particular, the high amount of phosphorus in iron ore could be a problem for energy consumption and CO2 emission in the steelmaking process. To reduce the impact of phosphorus, mainly two approaches: the utilisation of low-phosphorus iron ore, or dephosphorisation of high-phosphorus iron ore using mineral processing technology, have been suggested. In this paper, the removal of phosphorus from a low-grade high-phosphorus iron ore containing 0.1 mass% P and 57.5% Fe by alkaline roasting and wet grinding is discussed. The iron ore consists mainly of hematite, goethite, and quartz. Effects of sodium hydroxide concentration used as an alkaline source, roasting temperature, grinding time, and particle size on the dephosphorisation of highphosphorus iron ore were investigated. The dephosphorisation efficiency, iron loss, and mineralogical components of low-grade high-phosphorus iron ore under various experimental conditions were characterised by using XRD, SEM-EDS, and particle size distribution analysis. Results showed that the phosphorus content was lowered from 0.1 mass% to 0.034 mass%, while the iron grade reached 59.8 mass% from 57.5 mass% by alkaline roasting with 0.05 w/w NaOH at 300 °C for 2 h, followed by wet grinding in an attritor with water for 30 seconds at room temperature. Under the experimental conditions, the dephosphorisation rate was about 54.7%, and the solution obtained by wet grinding contained 22.7 mg/L of phosphorus and 21.5 mg/L of iron. The recovery rate of iron by this process reached 99.9%. Keywords: Iron ore, phosphorus, dephosphoriszation, alkaline roasting, wet grinding

Jan 1, 2020

By B. Aydin, A. S. Aloglu, S. Kahraman, E. Saygin

"The coal strength parameter is used in operations such as the selection and design of mechanical excavators and coal crushing/grinding equipment. However, coring or cutting prismatic specimens from coal for the standard strength tests is difficult, and sometimes not possible. For this reason a method for the indirect determination of coal strength from easy tests would be useful. In this study, the predictability of coal strength from the needle penetration test was investigated. This is a very easy and practical test method. Point load and needle penetration index (NPI) tests were carried out on coal specimens from Çayirhan coalfield in Turkey. The point load indexes were converted to the uniaxial compressive strength (UCS) values by using the general conversion factor. The UCS and NPI values were evaluated using regression analysis. A strong linear relationship was found between the two parameters. The conversion factor for the UCS-NPI ratio is 0.35 for the tested coal samples. It is concluded that the UCS of coal can be predicted from the NPI.IntroductionKnowledge of coal strength is important for the selection and design of mechanical excavators and coal crushing and grinding equipment. Uniaxial compressive strength of coal is used in designing pillar dimensions in room and pillar mining. Coals always contain bedding planes and cleats; they are also brittle and fragile. Therefore, coring or cutting prismatic specimens from coal for the standard strength tests is difficult, and sometimes not possible. For this reason, a method for the estimation of coal strength from easy tests would be useful.The needle penetration test is a nondestructive index test that is applicable both in the field and the laboratory and does not require any special sample preparation. The test has been used for the estimation of physical and mechanical properties of weak or soft rocks (Okada et al., 1985; Yamaguchi et al., 1997; Takahashi, Noto, and Yokokawa, 1988; Uchida et al., 2004; Aydan et al., 2006; Aydan, Watanabe, and Tokashiki, 2008; Aydan, 2012; Erguler and Ulusay, 2007; Park, Obara, and Kan, 2011; Ulusay and Erguler, 2012; Aydan and Ulusay, 2013; Aydan. Sato, and Yagi, 2014). This study investigates the predictability of coal strength from the needle penetration test."

Jan 1, 2017

Mill relining is a major contributor to overall plant downtime. Reducing the number of mill liner pieces removed from and replaced in the mill has a direct impact on the overall reline time and in turn, mill availability. To improve the mill availability of Ridgeway Operations' 32 foot SAG mill, a number of initiatives were implemented in terms of liner design. These included the conversion of the shell from 40 to 30 rows, reducing the number of pieces from 80 to 60 each shell reline and reducing the number of pieces from 48 to 32 per feed end reline. In addition, modifications were made to the discharge end of the mill to extend the life of the outer pulp lifter and discharge cone, thereby reducing the frequency of change out. The standard radial outer pulp lifter was converted to an angled design. The discharge cone was converted to the BullnoseTM design supplied by Bradken. This paper discusses the design changes made and the expected benefits to the Ridgeway Operations in terms of mill availability improvements.

Jan 1, 2007

By T. J. Otto, C. Musingwini

"The objective of any mining company is to sustainably maximize the net present value (NPV) throughout the life-of-mine (LOM). The expected NPV over the LOM is calculated based on a mine plan, yet the actual value realized by the mining company depends greatly on the level of intertemporal execution against the mine plan. Consequently, a major key performance indicator (KPI) that is often overlooked in open pit mining, due to a greater focus on temporal KPIs, is the degree of spatial compliance to the mine plan. Such focus sometimes leads to short-term actions being detrimental to long-term plans. In this paper we describe the development and implementation of a spatial mine-to-plan compliance reconciliation approach for an open pit mine. Application to a case study open pit iron ore mine in South Africa indicated a significant improvement in the spatial mine-to-plan compliance, from 69% to 94% over a three-year period from 2014 to 2016. These results indicate that implementation of the proposed spatial mine-to-plan compliance reconciliation approach can contribute positively to improving the level of spatial execution and assists in improving the alignment between short-term, medium-term, and LOM plans.IntroductionThe objective of any mining company is to maximize the net present value (NPV) throughout the life of mine (LOM). However, this objective needs to be fulfilled in a sustainable manner that considers the needs of various stakeholders, including employees, shareholders, and local communities where the mines operate. The expected NPV is calculated using a mine plan as a basis. Mine planning broadly involves identifying a strategy to exploit the mineral resource in a way that maximizes value at an acceptable level of risk throughout the LOM (Tholana and Neingo, 2016).The mine planning process is a well-recognized component in the mining value chain of an open pit mine. Figure 1 reflects the relative position of mine planning within a typical open-pit mining value chain from the mineral resource to the market"

Mar 1, 2019

By A. Galibois, A. Dubé, H. Monette, J. L. Collins

"The start of mining operations often raises serious financial problems. In marginal cases promoters frequently demand financial aid from governments.In the past, the financial assistance has taken the form of gifts, procurement contracts, etc., but aid in such form has been severely criticized. A new formula has been developed to provide a more equitable distribution of the revenues accruing to the government and to private capital.The benefits to these two parties have been evaluated in an hypothetical case and compared in terms of internal rates of return on their investment, their shares of the undiscounted cash flows and their primary profits.The method based on the non-zero sum game theory provides a means for suggesting the lowest feasible annual production and the optimal sum contributed by the government in the form of outright gift, equity capital and convertible bonds. Other financial hypotheses can also be optimized by the computerized analysis."

Jan 1, 2014

By and Z. S. Abisheva, Z. B. Karshigina, Ye. G. Bochevskay, A. S. Sharipova

The production of precipitated silica in the United States is about 145,000 tons of SiO2 and its prices vary significantly (from $ 1 to $ 4.5 per kg) depending on the area of its application. One of the most important parameters is its specific surface characterising dispersion (particle size and shape, presence or absence of pores), at a certain value of which the material acquires new properties and quality. At present, a technology has been developed for processing slag from phosphorus production to produce precipitated silica (‘white soot’) with a high specific surface and the possibility of extracting valuable components such as rare-earth metals (REMs) into a product enriched with them has been shown. However, the content of impurities in the deposited silicon dioxide, such as aluminum and iron, is above acceptable limits and may affect the quality of the final products. Therefore, along with the structure and specific surface, a very important characteristic of ‘white soot’ is the chemical purity of the material. In turn, calcium oxide occupies a significant share in the concentrate of rare-earth metals, which affects the content of ΣREMs oxides, which does not exceed 17.3 %. The low content of a valuable component may affect the feasibility of further processing. For the most complete utilisation of phosphorus slag, the authors propose a method for their acid processing, which allows for minimising the conversion of impurities to finely divided silica and collective concentrate, which will improve the quality of these products. Keywords: Phosphorus slag, precipitated silicon dioxide, rare earth metals, leaching, white soot, specific surface, technology

Jan 1, 2020

Notices STRASZACKERREPORT The Institute has received, for its information, a copy of the following letter, which was addressed to The Federation of Societies of Professional Engineers: REPORT: COMMISSION OF ENQUIRY INTO THE METHODS OF TRAINING FOR UNIVERSITY DEGREES IN ENGINEERING (STRASZACKER REPORT) Geagte Heer, VERSLAG: KOMMISSIE VAN ONDERSOEK NA DIE METODE VAN OPLEIDING VIR UNIVERSITEITSGRADE IN INGENIEURSWESE (STRASZACKERVERSLAG) Second International Symposium on Jet Cutting Technology This symposium, sponsored and organised by BHRA Fluid Engineering, of Cranfield, England, is to be held at St John's College, Cambridge, from 2nd to 4th April, 1974. Competition for student members of the South African Institute of Mining and Metallurgy Each year the Institute offers a prize (or prizes should the entries warrant it) of up to R100 for the best paper or dissertation on a topic appropriate to the interests of the Institute. Techomin 74 - World Mining Fair The above World Mining Fair, under the sponsorship of the International Committee for the Organization of World Mining Congresses and the Peruvian Government, is to be held in Lima, Peru, from 3rd to 12th November, 1974, to coincide with the 1974 World Mining Congress, which is to be held in Lima. NIM Reports Report No. 1435 The determination of chromium, manganese, iron, cobalt, and nickel by atomicabsorption spectrophotometry using the nitrous oxide-acetylene flame. Report No. 1463 Liq'uidus temperatures and activities of manganese (11) oxide in slags associated with the production of high-carbon ferromanganese alloys. Report No. 1467 The spectral analysis of solutions. 1. The analysis of rare-earth minerals. Report No. 1479 Infrared studies of the adsorption of oleate species on mineral surfaces,with special reference to fluorite. Report No. 1483 The South African manpower requirements in extractive metallurgy. Report No. 1484 Cost estimates for the production of copper wirebars from sulphidic ores. Report No. 1486 Review of the jluoro-chemical industry of the World. Report No. 1490 The adsorption of krypton, nitrogen, and water vapour on sodium oleate. Report No. 1491 Technology and economics of the Olaus kiln under South African conditions. De Beers Report The dry grinding of tungsten carbide/ steel combinations with diamond wheels. Metallurgical Directory The Israel Export Institute has just published the first edition of the Israel Metal Industry Directory, which gives pertinent information relating to the 750 Israeli manufacturers of metal products-addresses, annual turnover, and products- and to consulting engineers and export companies specializing in metal products. Visiting Nuclear Scientist The National Institute for Metallurgy has announced that Professor Vincent P. Guinn, of the University of California, is to spend his sabbatical leave (April to June) working with the Activation Analysis Research Group of the National Institute for Metallurgy.

By H. W. Glen

The use of a personal style (mainly active voice and first person) makes technical writing more pleasant to read, and helps the writer to express his meaning clearly and to avoid many of the stylistic errors normally encountered in that type of writing.

Jan 1, 1979

By John Austin, Graham Pingram

The idea of GOLD 100, an international conference on gold, was first conceived by Mr Les Haughton of Mintek in mid 1984. By the beginning of 1985, plans were well advanced to hold what was to be the most comprehensive conference on gold ever organized. Appropriately, GOLD 100 was timed to coincide with the celebration of Johannesburg's centenary. Leaching The South African Institute of Mining and Metallurgy will hold a two-day colloquium on the topic of leaching on 8th and 9th November, 1988, with the objective of bringing the latest developments in leaching technology to the attention of the mineral-processing industry.

Jan 1, 1988

By K. Harlow

"Zircon is a naturally occurring radioactive material (NORM) and as such is subject to a variety of regulations around the world. The regulatory processes and their implementation are summarized and the key issues affecting zircon and zirconia highlighted. Having absorbed the activities of the former Zircon Minerals Committee, the strategy of the Zircon Industry Association (ZIA) is to be the ‘go-to place’ for information on these matters, and its activities in the NORM space are described. Chemical industry regulations such as REACH are spreading around the world, and the paper provides an update of their status in the key jurisdictions. As mineral sands are transported to market in oceangoing vessels, they are subject to the regulations of the International Maritime Organization, which are summarized in the paper. IntroductionFrom a global perspective, zircon is generally not found in high concentrations other than in placer and dune deposits where it has been deposited along with other heavy minerals such as ilmenite, rutile, and monazite. Such deposits have been sorted and concentrated over geological time by the action of tides, waves, and wind to form concentrated deposits of heavy minerals along old coastlines and in river beds and deltas. Consequently, zircon is mostly found in association with the principal titanium minerals ilmenite and rutile. These secondary concentrations in placer deposits provide the commercial sources of zircon.All geological materials contain natural radioactivity, although the term NORM (naturally occurring radioactive material) is mostly used for minerals and other materials with above-average uranium and thorium concentrations. Importantly, the radioactive nature of zircon has not changed, but the way in which radioactivity is viewed by regulators has, affecting the zircon industry throughout the value chain."

Jan 1, 2017