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Construction and Demolition Waste (CDW) is among the largest waste streams in the world. Therefore, within the Circular Economy concept, there is a growing interest in its reuse. The purpose of this work was to study the use of recycled aggregates (RAs) obtained by a specific separation method from CDW, replacing natural aggregates (NAs) in the manufacture of precast concrete elements, such as kerbstones and paver blocks. The physical and technological properties of precast products formulated with RAs were analysed in accordance with current regulations, comparing them with those of commercial products manufactured with NAs. The results indicated that partial or total substitution of NAs by RAs increased the water absorption and apparent porosity values of the precast elements while reducing the bulk density and compressive strength. However, all units manufactured with RAs showed breaking load values higher than the minimum required by EN 1338 and, in some cases, slightly higher average tensile strength values than the reference material. In addition, some of the compositions including RAs gave rise to pieces that, according to their flexural strength, were classified as class 1 and marked S in accordance with EN 1340. According to abrasion resistance, in most cases, the precast elements are classified as Class 4 and I (& LE;20 mm). Finally, precast concrete produced from RAs satisfies the tolerance requirements for classification as class 3 (& LE;1.5 kg m(-2)). Therefore, it could be suitable for use in high pedestrian or traffic areas., This research was partially supported by the Centre for the Development of Industrial Technology (CDTI) to the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), by the project "Eco-efficient concrete urban paving from mixed recycled aggregates obtained from CDW" (Ref.: IDI-20180931). This research has been partially supported by RENSMA (Research Centre for Natural Resources, Health and Environment), University of Huelva, Spain.

Titanium dioxide pigment, also called “titanium white” (or Pigment White 6), is an essential element in many manufacturing processes with minerals of significant economic importance: ilmenite, rutile, and anatase. Approximately 95% of titanium is consumed in the form of titanium dioxide (TiO2), a white pigment used for coating, paper, printing ink, paint, plastic, food, and, in addition, pharmaceutical, cosmetic, and textile industries. TiO2 pigment is characterized by its purity, refractive index, particle size, and surface properties, and its use as white pigment is due mainly to its high refractive index. Titanium dioxide pigments are manufactured by two routes: (1) the sulfate process (about 40% of total TiO2 production) and (2) the chloride process (about 60%). Valorization of the waste generated from industrial processes is an important area of the circular economy and, for that reason, the valorization studies of the wastes and coproducts generated will be analyzed.

The use of industrial byproducts as construction material can help to achieve sustainability in this industry. Phosphogypsum (PG) is a waste obtained in the phosphoric acid (PA) manufacturing process, produced in large quantities, especially from the soil fertilizer industry. Alternatively, in the disposal of these materials in landfill, several investigations have applied PG as a substitute for natural gypsum in the production of Portland cement to control the hydration reaction rate of cement and also in concrete, bricks, plaster panels, and others. The composition and characteristics of PG are closely related to both the composition and origin of the feedstock used (phosphate rock), showing high gypsum content, and high levels of natural radionuclides, especially from U-series. These properties depend on the PA production process and the origin of the raw material. In this chapter, the possibilities of using this waste in cement-based materials are presented, to encourage future research lines based on this waste/byproducts.

A new method for the determination of radium quartet (223,224,226,228Ra) in environmental samples by alpha-particle spectrometry with PIPS detectors is described. This uses 225Ra as yield tracer, in equilibrium at the beginning with 229Th. Thorium is removed from the sample by using AG1X8 anion-resin, and then radium isotopes are isolated and purified with a cation-exchange column Biorad AG50X8, verifying that Ac has been fully removed from the sample to ensure the good evaluation of the Ra yield (average decontamination factor > 92%). Finally, the counting source of radium is obtained by micro-precipitation with BaSO4. This method produces high spectral resolution ( 70%). In this new method, NH4Ac in 0.1 M HNO3 is used to remove the 225Ac contained in the sample in order to avoid its future spectral interference in the yield calculation. The method has been validated by using certified reference samples with known concentrations of radium isotopes.

The phosphogypsum (PG) stacks located at Huelva (SW Spain) store about 100 Mt of PG, and covers a surface of 1000 ha. It has been very well established in many studies that this waste contains significant U-series radionuclides concentrations, with average activity concentrations rounding the 650, 600, 400 and 100 Bq kg−1 for 226Ra, 210Po, 230Th and 238U, respectively. However, the radionuclide transfer from this repository into the environment by the aquatic pathway will depend on the mobility of each radionuclide. The mobility of the natural radionuclides (U-isotopes, Th-isotopes, 226Ra, and 210Po) contained in the PG piles were evaluated by using the optimized BCR sequential extraction procedure (BCR “Community Bureau of Reference”). The radionuclides were measured in the liquid fractions by alpha-particle spectrometry with semiconductor PIPS detectors. In addition, to validate the obtained results, waters from different locations of the PG piles (pore-water, perimeter channel and edge outflow leachates) were taken and the alpha emitter radionuclides determined. Uranium presents the highest mobility, being its total mobile fraction in the PG around 70%, while 210Po and 226Ra present an intermediate mobility of (around 50% and 30%, respectively). And finally, the Th-isotopes have very low mobility (mobile fraction

Slag cleaning furnace flue dust is generated in the cleansing of copper slag and their reprocessing produces wastes considered hazardous materials. Due to their high metals content their disposal not offers any economic either environmental benefit. In view of this fact, the main objective was to gain basic information for the reuse of these wastes in different fields. So, an exhaustive characterization of two wastes have been carry out in order to determine their composition, mineral phases, particle size distribution and leaching capacity of contaminants, as an indispensable preliminary step to choose the best available technology to recover the metals. Both waste contain very fine particles size and are mainly enriched of Zn, Pb and Fe. Zincite (ZnO) is the major mineral phase in which Zn is presented in both wastes. Pb is found as carbonate (PbCO3) or sulphate (PbSO4). On the other hand, iron is presented as oxides and hydroxides (Fe3O4 and FeOOH). The results show that both wastes are an important secondary resource of Zn and Pb and pyrometallurgy and hydrometallurgy appears to be attractive options for the management of these hazardous materials. The value associated with the Zn and Pb recovery contributes significantly to the economic viability of the activity, since these processes are widely used to reprocess secondary source waste with similar composition to the studied wastes. In this sense, and taking into account a best available technology environmental friendly, the hydrometallurgy would ensure the best option for Zn and Pb recovery from the wastes studied.

Determining the availability of natural radionuclides in environmental conditions is increasingly important in order to evaluate their toxicity. A validated procedure is necessary to ensure the comparability and accuracy of the results obtained by different laboratories. For that, an optimised BCR sequential extraction procedure has been applied to the certified reference material (CRM), coded as BCR-701, and their resulting liquid and solid fractions were subjected to an exhaustive chemical and radioactivity characterisation. In this sense, several material characterisation techniques were used for chemical, mineralogical, and radioactive characterisation, in order to gain basic information about the obtained fractions. In accordance with the results of this work, the BCR sequential extraction procedure has been validated for the most significant alpha-emitter natural radionuclides (210Po, 234U, 238U, 230Th, 232Th, and 226Ra). It has been demonstrated that their mobility is related to the speciation under environmental conditions and the type of radionuclide; we have even found differences between radionuclides of the same element, such as the cases of the pairs 234U238U and 230Th232Th, for the BCR-701. In addition, we found that radium was mainly bound to the reducible fraction (Fe and Mn-oxyhydroxides), uranium to the oxidizable fraction (organic matter and sulphides), and that the polonium and thorium isotopes had a high affinity with the particulate phase (non-mobile fraction).

Commercial copper (Cu) is obtained by a hydro-pyrometallurgical process, where the Cu anodes obtained in the furnaces (Cu > 99.5%) are enriched up to 99.99% in “cathodes” by electrorefining at an electrolysis plant. During this process, some impurities accumulate in the electrolyte, mainly arsenic (As), which decrease the quality of the Cu cathode. For this reason, the electrolyte is sent to an electrolyte cleaning plant (ECP) for its purification. Electrolyte sludge (ES) is produced in the last stage of purification and is recirculated back to the furnace due to the high Cu content. This recirculation involves a severe problem of As accumulation in the industrial process. The objective of this work was to develop a procedure to fully dissolve the ES, removing the As and recovering its Cu content. The ES dissolution process was optimised (dissolution efficiency > 99%) in H2SO4 (1.4 M)/HNO3 (1.8 M) medium using a 1:20 g mL−1 solid-to-liquid ratio. As was removed from the ES solution by its precipitation as iron (III) arsenate, with high efficiency (more than 70%). After As removal, the Cu can be precipitated as copper sulphate, which is used in several applications.

Mercury (Hg) accumulation capacity was assessed in three plant species ( Axonopus compressus , Erato polymnioides , and Miconia zamorensis ) that grow on soils polluted by artisanal small-scale gold mines in the Ecuadorian rainforest. Individuals of three species were collected at two sampling zones: i) an intensive zone (IZ, 4.8 mg Hg kg -1 of soil) where gold extraction continues to occur, and ii) a natural zone (NZ, 0.19 mg Hg kg -1 of soil). In addition, the percentage of arbuscular mycorrhizal fungi (AMF) colonization was determined in plant roots and seven fungal morphotypes isolated from rhizospheric soil. Results suggest a facilitation role of native and pollution adapted AMF on Hg phytoaccumulation. E.g., E. polymnioides increased Hg accumulation when growing with greater AMF colonization. We concluded that E. polymnioides is a good candidate for the design of microbe-assisted strategies for Hg remediation at gold mining areas. The consortia between E. polymnioides and the AMF isolated in this study could be instrumental to get a deeper understanding of the AMF role in Hg phytoaccumulation.

In recent years, ceramics have played very significant roles in the immobilization of potentially hazardous waste. Currently, this technology is making a strong impression as an extremely advantageous processing technique for the consolidation of ceramics for the immobilization of waste. The heterogeneity of traditional clay-based materials accommodates a variety of wastes with no major loss of the properties of the final product. Consequently, some researchers have developed new applications using this waste as a clay-based ceramic material, that is, tiles (clay and porcelain stoneware), bricks, and even as lightweight aggregates. An initial description and characterization of the different wastes is summarized. The review also includes brief summaries of the different applications researched between 2015 and 2019, highlighting how they work when the waste is added to the ceramic. An evaluation of the environmental implications is also given. The analysis and evaluation of the vast amount of experimental research have shown that these varieties of waste are potentially valuable as a ceramic material resource for the manufacture of clay-based ceramic products, where waste can be used as a substitute for expensive natural resources, improving the products’ physical, mechanical, and environmental performance, with no significant environmental impacts.

The industry devoted to the production of phosphoric acid by using as raw material sedimentary phosphate rock (PR) is considered as a NORM activity (Naturally Occurring Radioactive Materials), due to the high levels of U-series radionuclides contained in this ore, which are 1–2 orders of magnitude higher than those in unperturbed soils. This fact allowed us to develop a deep characterization of the raw materials, wastes, main intermediate materials, and final products obtained at a typical phosphoric acid factory. The elemental composition (major, minor and trace elements), radionuclide concentrations, grain size distribution, mineralogy and micro-structural composition were analyzed. The aim of this characterization was to obtain information for operators and maintenance personnel involved in clean-up and waste management operations. The highest concentrations of some heavy metals and radionuclide activity concentrations were found in the “scales” (or internal incrustations)from the pipes that carry either phosphoric acid (PA) or the phosphogypsum waste (PG). The highest concentrations where found for 226Ra and 40K,with values up to 9 and 5 Bq g−1, respectively. In addition, high concentrations of many toxic heavy metals and trace elements, such as Cd, Cr, Ni, Sr, Y, V, Zn, Th, and U, were found in some sludge samples. The shielding effect of the containers/vessels/pipes has an essential role in the measured external dose in the intermediate products. The radiological implications of natural radionuclides with higher activity showed that if the maximum particulate matter concentration established in the Spanish regulation is verified, and taking into account the most conservative scenario, the annual limit of 1 mSv y−1 is not exceeded.

Next to the city of Huelva (SW of Spain), around 100 Mt of phosphogypsum (PG) are stored in stacks on the salt-marshes of the Tinto River estuary covering a surface of about 1000 ha. Due to the high content of 238U series natural radionuclides of the PG, its acidic nature (pH about 3), and the fact that PG stacks were disposed without any kind of isolation from the substrate, they could produce a potential radioactive impact into the underlying sediments. The aim of this work is to assess the pollution of the underlying sediments by natural radionuclides coming from the PG stacks. To this end, seven cores were taken, and PG and sediments samples collected at different depths were analysed. The activity concentrations of the main long half-live natural radionuclides of interest were determined by applying both gamma-ray and alpha-particle spectrometry radiometric techniques. The results of this study showed that the first decimeters of salt-marsh sediment act as a “barrier” for the radionuclides coming from the PG stacks decreasing rapidly its activity concentration in depth, affecting mainly sediments located in the first 20 cm below the contact due to mixing processes. While 230Th, 226Ra and 210Pb pollution is mainly restricted to the first 20 cm of sediments, U-isotopes can reach higher depths (up to around 50 cm) by leaching processes due to their lower reactivity and higher concentration in the polluted leachates. The obtained results have high relevance for the design of the perimeter channel which is projected to build in the restoration project, suggesting that should has around 1 m deep under the base of the PG stacks, to ensure the full collection of polluting leachates, and to prevent their release into the estuary of the Tinto River.

The province of Huelva is one of the areas most affected by acid mine drainage (AMD) in the world, which can produce big enhancements and fractionations in the waters affected by AMD. There are very few studies on this issue, and none on polonium-210. Twenty-two water reservoirs were sampled, and the 210Po was measured in both dissolution and particulate phases. The 210Po concentrations in the waters were in the same order of magnitude to those ones for unperturbed systems, although the data published to particulate matter are very scarce. A mean value and standard uncertainty for 210Po of 0.25 ± 0.03 mBq L−1 in the dissolved matter, and 62 ± 9 mBq g−1 in the particulate matter can be established as base line for the reservoirs of the Huelva area. The distribution coefficients (kd) range from 104 to 106 L kg−1, in agreement to the found ones by other authors for the case of neutral waters, but being the lowest values for the more acidic reservoirs. It has been also found that 210Po has a high tendency to be associated to the particulate matter for neutral-alkaline waters, however, under extreme acid conditions (pH < 3), increases the Po tendency to be associated to the dissolved phase. Therefore, the main conclusion obtained in this work is that AMD has no a significant influence on the total activity concentration of 210Po in the waters of reservoirs, but the acidity has a clear influence on its distribution between both dissolved and the particulate phases., This research has been partially supported by the research projects “U–Th–Ra isotope fractionation mechanisms under extreme natural acidic conditions (CGL2012-32860), and “Characterisation and modelling of the phosphogypsum stacks from Huelva for their environmental management and control (P10-RNM-6300)”. This is the publication number 112 from CEIMAR Publication Series., info:eu-repo/semantics/publishedVersion

Phosphogypsum (PG) is disposed worldwide in large stacks usually placed in coastal zones, as in the case of Huelva (SW of Spain), where around 100 Mt of PG are stored on the salt marshes of the Tinto River estuary covering a surface of about 1000 ha. This management generates the weathering of PG, and due to its high acidity (pH ≈ 2) and pollutant load can provoke significant emissions into their surroundings. In this work were evaluated by laboratory experiments the effects of pH increase in the behaviour of heavy metals and natural radionuclides during the mixing of phosphogypsum leachates with seawater. The acidic phosphogypsum leachates showed concentrations of heavy metals from two to three orders of magnitude higher than natural continental waters, and natural radionuclides (U-isotopes and 210Po) from four to five orders of magnitude higher than unperturbed aquatic systems. Major elements and some heavy metals as Mn, Ni, Cd, As, Sb and Co showed a conservative behaviour during the neutralisation of the leachates with seawater, remaining in the liquid phase, while other ones as Al, Fe, Cr, Zn, Cu, Pb precipitated and/or were adsorbed onto the solid phase. The U-isotopes and 210Po showed a clear non-conservative behaviour probably due to coprecipitation/adsorption processes onto the formed precipitates, but while 210Po reached a total removal at pH ≈ 7, U- isotopes after a total removal at pH ≈ 5 returned into the liquid phase due to redissolution/desorption processes at near neutral pH. The formed precipitates, mainly composed by iron phosphates particles, showed heavy metal and natural radionuclide concentrations from one to three orders of magnitude higher than unperturbed soils. All these facts demonstrate the serious environmental impact produced by the PG stacks into their surroundings and the urgency of effective restoration measures., This work was partially supported by Spanish Ministry of Economy and Competitiveness [project number, CTM2015-68628-R], the Spanish Ministry of Science, Innovation and Universities [project number, EQC2018-004306-P], the Regional Government of Andalusia [project number, FEDER2018-UHU-1255876] and the Spanish Ministry of Education [grant number FPU15/00646].

This research was focused on the analyses of the hydrochemical behaviour of long-lived natural radionuclides (210Po, 210Pb, 234,238U, 230,232Th, 226,228Ra) in groundwaters from Spanish aquifers with different geological characteristics and the evaluation of the dose by ingestion of these waters. The study was performed by the gross alpha-beta, alpha spectrometry and physicochemical analysis of a set of bottled drinking waters. Radionuclide activities in the investigated aquifers were highly variable. High concentration of 210Pb is associated with granitic bedrock and reducing conditions. On the other hand, the highest 238,234U concentrations were found in carbonate aquifers. Activities of 226Ra are largely controlled by ion exchange reactions due to the presence of relatively high concentration of chloride. Several waters exceeded the parametric value for gross alpha mainly due to 234U, 226Ra and/or 210Pb concentrations. Moreover, the content of 226Ra and 210Pb in the water contributed mainly to the indicative dose.

Proceedings of the 9th International Topical Meeting on Industrial Radiation and Radioisotope Measurement Applications, celebrado en Valencia (España) del 6 al 11 de julio de 2014., Industrial activities involving Naturally Occurring Radioactive Materials (NORM) are found among the most important industrial sectors worldwide as oil/gas facilities, metal production, phosphate Industry, zircon treatment, etc. being really significant the radioactive characterization of the materials involved in their production processes in order to assess the potential radiological risk for workers or natural environment. High resolution gamma spectrometry is a versatile non-destructive radiometric technique that makes simultaneous determination of several radionuclides possible with little sample preparation. However NORM samples cover a wide variety of densities and composition, as opposed to the standards used in gamma efficiency calibration, which are either water-based solutions or standard/reference sources of similar composition. For that reason self-absorption correction effects (especially in the low energy range) must be considered individually in every sample. In this work an experimental and a semi-empirical methodology of self-absorption correction were applied to NORM samples, and the obtained results compared critically, in order to establish the best practice in relation to the circumstances of an individual laboratory. This methodology was applied in samples coming from a TiO2 factory (NORM industry) located in the south-west of Spain where activity concentration of several radionuclides from the Uranium and Thorium series through the production process was measured. These results will be shown in this work., This research has been partially supported by the Spanish Nuclear Safety Council (Grant no. CSN 2004-001) through the project “Radiological Impact associated with Non-Nuclear Industries from South of Spain”, and by the Spanish Department of Science and Technology (Grant no. CTM 2009-14321-C02-01-02) through the Project “Determination of scavenging rates and sedimentation velocities using reactive particle radionuclides in coastal waters; application to pollutants dispersion”.

The main objective of this paper is focused in the use of waste generated by the TiO2 pigment industry, ilmenite mud (MUD), on the production of ceramic bodies. These ceramic bodies were produced from mixtures of a commercial red stoneware mixture (RSM) with different concentrations of mud (3, 5, 7, 10, 30 and 50 wt%). The samples were sintered to simulate a fast-firing process. The sintering behaviour of the fired samples was evaluated according to ISO rules by linear shrinkage, water absorption and porosity measurements. Both green powder and fired samples were characterised by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC/TG), field emission scanning electron microscopy (FESEM) and bending strength measurements. Moreover, the activity concentrations of radionuclides were measured by high-resolution low-background gamma spectrometry, because this mud is a NORM (Naturally Occurring Radioactive Material) waste. Finally, the TCLP leaching test (Toxicity Characteristic Leaching Procedure, USEPA) was performed to assess the risks of use tiles from an environmental perspective. The results demonstrated that MUD can be successfully valorisated in the manufacture of red stoneware ceramic bodies with similar, or even better technological properties than commercial materials used currently.

In this paper a call is performed in support of the valorization of some by-products generated in the production processes of some NORM industries. In spite of a traditional management of these by-products based either in their direct releases to the environment or their disposal under control in big areas, their use attending to their characteristics in fields as agriculture, construction of buildings, construction of roads, in landfills, etc. should be promoted. These applications will minimize the environmental and public radiological impact of these by-products, generating at the same time economic benefits to the NORM industries involved.

In this paper, the use of red gypsum (RG), waste from the naturally occurring radioactive materials industry that is devoted to the production of the TiO2 pigment, was evaluated as a source of calcium for CO2 sequestration by an indirect carbonation process. The main objective was to valorise this waste and, at the same time, analyse the reduction of greenhouse gas emissions (CO2) emitted by industrial sources that use this process. In order to induce the carbonation process, the extraction of calcium from the sample was required beforehand. For this, two different extraction routes were applied (the NaOH and NH4OH pathways). The obtained results demonstrate that RG has high carbonation reactivity, depending on the extraction agent used at room temperature and pressure. The conversion of RG to calcium carbonate was 92% when using sodium hydroxide, whereas 64% was obtained with ammonium hydroxide extracting. The behaviour and fluxes of the radionuclides and trace elements, initially contained in the RG, were also evaluated during the full carbonation process. In general, the levels of pollutants in the final calcite (calcium carbonate) were comparable to the ones found for typical unperturbed soils.

Phosphogypsum (PG) is a waste from phosphoric acid production, and this work evaluates the use of PG as an additive in ceramic manufacturing. Ceramic samples were produced by adding different concentrations of PG (5, 7.5, and 10 wt%) to natural clay, and sintering at 950, 1050, and 1150 °C. Technological and mechanical properties of the obtained ceramics were evaluated. Moreover, the U.S. EPA's toxicity characteristic leaching procedure, Index “I”, and the effective radium activity were calculated to evaluate the environmental risks. The use of PG improves the sintering behaviour and the bending strength, while also the environmental impact is negligible., This research has been partially supported by the Spanish Government Department of Science and Technology (MINECO), by the project “Fluxes of radionuclides emitted by the PG piles located at Huelva; assessment of the dispersion, radiological risks and remediation proposals” (Ref.: CTM2015-68628-R). PhD student M. Contreras would like to express his gratitude for the research contract granted to him through the Fellowship Training Program of the University Teaching Staff (Ref.: AP2010-2746), financed by the Spanish Ministry of Education, Culture and Sport (MECD). This research has been partially supported by São Paulo Research Foundation (FAPESP) (Ref.: 2013/07296-2) in the Center for the Development of Functional Materials (CDMF), Laboratory of Ceramic Materials (LaMaC/UNESP), Campus of Presidente Prudente, São Paulo, Brazil.

Various treatments of phosphogypsum samples extracted in Huelva, Spain, curing conditions and incorporation ratios were studied to evaluate the viability of being used as set regulator or as supplementary cementitious material to improve the mechanical behaviour of cement mortars. The physical-chemical properties, mechanical behaviour and environmental impact of these phosphogypsum-based cement mortars were determined. It was concluded that the phosphogypsum treatments and curing conditions influence the mineralogical transformations of mortars and therefore also the mechanical behaviour of the mortars tested. Furthermore, the heavy metal impurities in the phosphogypsum were immobilized in the cement matrix, leading to a clear improvement of the technical properties of cement mortars made with this waste compared to the traditional use of natural gypsum.

Under acid mine drainage (AMD) conditions, the solubilities and mobilities of many elements are vastly different from conditions prevailing in most natural waters. Studies are underway in the Río Tinto area (Iberian Pyrite Belt), in order to understand the behavior and mobility of long-lived U-series radionuclides under AMD conditions. A set of leaching experiments utilizing typical country rocks from the Tinto River basin, waste rock pile composite materials, iron-rich riverbed sediments and gossan (weathered naturally rock) were performed towards this purpose. Initial leaching experiments using distilled water kept in contact with solid material for 300, 100, 50 and 1 h resulted in very low concentrations of U with (234)U/(238)U activity ratios close to equilibrium and activity concentrations of (210)Po 0.03 mBq/g. Leaching experiments performed with sulfuric acid media (0.1 and 0.01 M), and contact times between the solid and solution for 24 h were conducted to quantify the amount of U-isotopes and (210)Po leached, and the radioactive disequilibria generated between the radionuclides in the leachate. These experiments show that Po mobility in acidic conditions (pH around 1-2) is very low, with (210)Po activity in the leachate to be 6% in average for the solid sample. By contrast, mobility of U-isotopes is higher than that of Po, around 1.2%.

Titanium is a very important element for several industrial applications, being one of the ninth most abundant elements in the Earth’s crust (0.63% wt). In this work it will discuss the different mining and industrial activities involved in the production of titanium dioxide. The first step analyzed will treat about the beneficiation mining process of titanium mineral, and secondly, it will discuss the two main processes of the TiO2 manufacturing (sulphate and chloride routes). In addition, we will show different uses of the titanium dioxide pigment as filler in paper, plastics and rubber industries and as flux in glass manufacture, etc. Finally, we will show that the old wastes are currently called co-products since they were valorized, being commercialized by the Spanish industry of TiO2 production in different fields such as agriculture, civil engineering, or cement manufacturing.

In this research, a new type of phosphogypsum–sulfur polymer cement (PG-SPC) for use in the manufacture of building materials was obtained. Physicochemical, radiological characterization, and modeling of exhalation rates were carried out in phosphogypsum (PG) and PG-SPC samples. Because the PG is enriched in several natural radionucleides, a leaching study in PG-SPC was performed. The optimized ratio of elemental sulfur/phosphogypsum=1∶1.0 and phosphogypsum dosage = 10–40% by weight was obtained. The result showed that the solidified materials present a highest strength (54–62 MPa) and low total porosity (2.8–6.8%). The activity concentration index (I) in the PG-SPC is lower than the reference values in most international regulations; therefore these new sulfur polymer cements can be used without radiological restrictions in the manufacture of building materials inside a standard room (5×5×2 m3) with good ventilation. The leaching experiment demonstrated that the environmental impacts of the PG-S...

A study about the distribution of several radionuclides from the uranium and the thorium series radionuclides along the production process of a typical NORM industry devoted to the production of titanium dioxide has been performed. With this end the activity concentrations in raw materials, final product, co-products, and wastes of the production process have been determined by both gamma-ray and alpha-particle spectrometry. The main raw material used in the studied process (ilmenite) presents activity concentrations of around 300 Bq kg−1 for Th-series radionuclides and 100 Bq kg−1 for the U-series ones. These radionuclides in the industrial process are distributed in the different steps of the production process according mostly to the chemical behaviour of each radioelement, following different routes. As an example, most of the radium remains associated with the un-dissolved material waste, with activity concentrations around 3 kBq kg−1 of 228Ra and around 1 kBq kg−1 of 226Ra, while the final commercial products (TiO2 pigments and co-products) contain negligible amounts of radioactivity. The obtained results have allowed assessing the possible public radiological impact associated with the use of the products and co-products obtained in this type of industry, as well as the environmental radiological impact associated with the solid residues and liquid generated discharges.

This work analyzes and evaluates the main mechanical, elastic and thermodynamic properties of cements manufactured with different proportions of red gypsum (RG), a waste generated by the titanium dioxide industry. The results show that red gypsum can be used as a safe substitute for natural gypsum in the manufacturing of commercial cements with no reduction in quality. In addition, the mobility of the original pollutants in red gypsum is negligible in the cements made from this waste, with the quantities of leached pollutants similar to those measured in standard reference cements formed with natural gypsum.

In order to fill a gap in the open literature, occupational exposures and activity concentrations have been assessed in two NORM industrial plants, located in the south-west of Spain, devoted to the production of mono-ammonium phosphate (MAP) and di-ammonium phosphate (DAP) fertilisers. The annual effective doses received by the workers from these plants are clearly below 1 mSv yr(-1) and the contribution due to external radiation is similar to that due to inhalation. The contribution to the maximum effective doses due to inhalation of particulate matter has been estimated to be about 0.12 mSv yr(-1), while the (222)Rn concentrations inside the plants are of no concern. Consequently, no additional actions or radiological protection measures need to be taken to decrease the natural radiation received by the workers in these facilities.

Phosphogypsum (PG), primary by-product from phosphoric acid production, is accumulated in large stock-piles which were active until 2010, when spills were banned. It is considered as NORM material that contains radionuclides from 238U and decay series which are of most radiotoxicity. PG was valorized and/or recycled in a building material, sulfur polymer cement (SPC). The SPC-PG samples reach the international regulation to use in the manufacture of building materials without radiological restrictions, except the sample with the 50% of PG. Under normal conditions of ventilation the contribution to the expected radon indoor concentration is also below the international recommendation.

Two wastes, red gypsum (RG) and unattacked ilmenite (known as tionite), from the titanium dioxide production industry have been used to study the possibility of manufacturing new fire-isolating materials, and for that they were characterized for mineralogical composition and thermal behavior. Tests have demonstrated that these wastes could be used for fire insulation. Thermogravimetry analysis (TGA) of the thermal behavior of these wastes and tests on the new isolating materials against temperature indicate that they do not undergo significant chemical and structural changes up to about 1000 °C.

In several Naturally Occurring Radioactive Material (NORM) industries, relatively high temperatures are used as part of their industrial processes. In coal combustion, as occur in other high temperature processes, an increase of the activity concentration of every natural radioisotope is produced both, in residues and by-products. An additional increase can be observed in the activity concentration of radionuclides of elements with low boiling point. This work is centred in the increase of polonium, more precisely in its radioisotope Po-210, present in the natural chains, and with a half-life long enough to be considered for radiation protection purposes. This additional increase appears mainly in the residual particles that are suspended in the flue gases: the fly-ashes. Besides, scales, with a high concentration of this radioisotope, were observed. These scales are produced on surfaces with a temperature lower than the boiling point of the chemical element. Both, the accumulation in particles and the production of scales are attributed to condensation effects. When effective doses for the public and the workers are evaluated, taking into account these increases in activity concentrations, the use of theoretical models is necessary. In this work a theoretical description of those effects is presented. Moreover, a verification of the predictions of the model was performed by comparing them with measurements carried on in coal-fired power plants. The same description here presented is applicable in general to the behaviour of Po-210 in other NORM industries where high temperature processes involving raw materials are used, as can be ceramic, cement production, tiles production or steel processing.

The present study was conducted to characterize several raw materials and co-products from the titanium dioxide industry in relation to their elemental composition (major, minor and trace elements), granulometry, mineralogy, microscopic morphology and physical composition. The main objective was to gain basic information for the future potential application of these co-products in fields such as agriculture, construction, civil engineering, etc. Microscopic studies were performed by applying scanning electron microscopy with X-ray microanalysis (SEM-XRMA) while the mineralogical compositions were analysed by means of the X-ray diffraction (XRD) technique. The concentrations of major elements such as Na, Al, Si, Ca, Ti, Fe, S and K were determined by X-ray fluorescence (XRF), while heavy metals and other trace elements were determined by ICP-MS. The physicochemical characterization of the raw materials used in the titanium dioxide industry, in addition to the characterization of the co-products generated, has enabled the evaluation of the degree of fractionation of different elements and compounds between the different co-products, as well as the control of the possible variations in the physicochemical composition of the raw materials throughout the time and the study of the influence of these variations in the characteristics of the obtained co-products. As a main conclusion of our study, it is possible to indicate that the levels of the pollutant elements associated to the co-products analysed were, in general, within safe limits and, therefore, they could potentially be used in composites as fertilizers or for building materials in road construction, etc. Nevertheless, for the specific application of each of these co-products in agriculture, construction and civil engineering, additional studies need to be performed to evaluate their appropriateness for the proposed application, together with specific studies on their health and environmental impact.

A study was undertaken with the aim of identifying a suitable plant for the phytoremediation of metal-polluted soil from an artisanal mining area in Ecuador. Three zones including a natural zone (NZ), abandoned zone (AZ) and intensively mined zone (IZ) were selected. Three common native plants grown in the three zones were identified and collected, including Miconia zamorensis, Axonopus compressus and Erato polymnioides. The percentage of arbuscular mycorrhizal colonization that benefits their own survival in polluted soil was analyzed in the root samples of these candidate species. Analysis of the soils and plants collected from the different zones showed that the concentrations of Pb, Zn, Cu and Cd were comparatively lower in the NZ, higher in the AZ and IZ, and highest in the AZ for all the metals. The concentration of all these metals in plant tissues was the highest in E. polymnioides. The data analysis including the metal accumulation index, bioconcentration factor and translocation factor strongly identified E. polymnioides as a hyperaccumulator plant suitable for phytoremediation.

Trabajo presentado al "EU NORM 2 Symposium" celebrado en Praga (República Checa) del 17 al 19 de junio de 2014., En programa: "Preliminary Steps in the Restoration of a Phosphogypsum Disposal Site: Radioactive Characterization of Leachates and Efflorescences Affecting the Surrounding Area"., After the recent closing of some phosphoric acid plants located in the South-West of Spain, it has been decided to restore a big extension (more than sixty hectares) of saltmarshes where historically some million tonnes of phosphogypsum (PG), the main byproduct generated by these plants, have been disposed of. This PG is characterized for containing high activity concentrations of several radionuclides from the uranium series, mainly 226Ra, 210Pb and 210Po and to a lesser extent U-isotopes. The PG disposal area can be considered as a potential source or radionuclides to their nearby environment, through the waters which percolate from them and through the efflorescences formed in their surroundings. A previous detailed radioactive characterization of the mentioned waters and efflorescences has been considered essential for a proper planification of the restoration plan to be applied in the near future in the zone.

The effects of noise are particularly harmful for the newborns, and therefore this study assesses and characterizes noise levels in a neonatal intensive care unit (NICU) in a medium-size hospital in the city of Huelva with the aim of optimizing the management and quality of care for newborns. The equivalent continuous sound level was recorded as A-weighting curves using Type I sound level meters with levels measured during 100 milliseconds along to 15-day period in the both critical (in and out of incubators), and intermediate care units from a medium-size hospital. These devices were attached to a central beam 80 cm below the ceiling and into one of the incubators. The maximum noise levels measured for critical (C-in), C(out) and intermediate (I) were: 88.8 dBA, 97.2 dBA and 92.4 dBA, respectively, while for the equivalent noise levels for the total measuring period (15 d) were 57.0 dBA, 63.7 dBA, and 59.7 dBA, respectively. The Fourier frequency analysis has demonstrated several typical periods related to both work activities and family visit, which were: 7 days, 24 h, 12 h, and 3 h. The statistical analysis revealed a clear correlation between the noise level, the kind of care room, and the time of the day. The results show that the values recommended by international bodies and agencies (AAP, WHO) are surpassed by a large margin, thus making it crucial that certain norms are followed in order to reduce the noise level in the NICU, by means of physical alterations to the layout, and raising awareness of health care personnel and visitors in order to encourage noise prevention in the daily care work and conversation. And finally, has been demonstrated that by applying the t-Student test the mean noise values in both wards are significantly different, which leads us to state that the noise level for the critical wards are higher than in the intermediate care ward.

The aim of this work is to prepare a new type of phosphogypsum-sulfur polymer cements (PG-SPC) to be utilised in the manufacture of building materials. Physico-chemical and radiological characterization was performed in phosphogypsum and phosphogypsum-sulfur polymer concretes and modeling of exhalation rates has been also carried out. An optimized mixture of the materials was obtained, the solidified material with optimal mixture (sulfur/phosphogypsum. =1:0.9, phosphogypsum dosage. =10-40. wt.%) results in highest strength (54-62. MPa) and low total porosity (2.8-6.8%). The activity concentration index (I) in the PG-SPC is lower than the reference value in the most international regulations and; therefore, these cements can be used without radiological restrictions in the manufacture of building materials. Under normal conditions of ventilation, the contribution to the expected radon indoor concentration in a standard room is below the international recommendations, so the building materials studied in this work can be applied to houses built up under normal ventilation conditions.Additionally, and taking into account that the PG is enriched in several natural radionuclides as 226Ra, the leaching experiments have demonstrated that environmental impact of the using of SPCs cements with PG is negligible. © 2011 Elsevier B.V.