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Structural and vibrational behaviour of pyromorphite-vanadinite solid solution series

Solecka U., Bajda T., Topolska J., Manecki M.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 1

135--136

EN

Pyromorphite Pb5(PO4)3Cl and vanadinite Pb5(VO4)3Cl belong to the apatite supergroup. They are secondary minerals formed in the oxidation zones of lead ore deposits. Both crystallize in hexagonal symmetry with the space group P63/m (Dong et al. 2002). The crystal structure of these two minerals allows to accommodate both metal cations and anionic complexes. It is the reason, why pyromorphite and vanadinite forms solid solution series. Isovalent replacement of P with V is one of the most common anionic substitution. Lead apatites are one of the least soluble along apatites group minerals and characterized by high thermal stability (Dong et al. 2002, Flis et al. 2011). Characteristic properties of apatite structure cause that these minerals are successfully used in many fields, especially for the immobilization of toxic waste and lead-contaminated soil (Ma et al. 1993, Chen et al. 1997, Dong et al. 2002, Kim et al. 2005). So far, pyromorphite and mimetite are the most known and used for the immobilization of lead. Pyromorphite and mimetite are isostructural with vanadinite, therefore it has been predicted that this mineral is also important for the environment. Accordingly, the aim of this study was to characterize of the pyromorphite-vanadinite solid solution series. This research presents systematic changes in the structure of these minerals. Pure pyromorphite and vanadinite and minerals with intermediate compositions Pb5(TO4)3Cl, where T = P + V, of various P/V ratios were synthesized from aqueous solutions at 298 K and pH = 3.5. Synthetic solids were analyzed by X-Ray diffraction (XRD), infrared absorption spectroscopy (FTIR) and Raman spectroscopy. Based on the X-Ray analysis, it was found that synthetic precipitates represent homogeneous phases of pyromorphite and vanadinite, which have intermediate chemical composition. Diffraction peaks of pyromorphite-vanadinite solid solution series were shifted due to replacement of PO4 by VO4. Replacement of PO4 by VO4 anions is causing changes in the structure of apatite and hence these shifts. Unit cell parameters of studied solid solutions show a linear variation. In the FTIR and Raman spectra of pyromorphite-vanadinite solid solutions series, the bands which are characteristic for vibrations of P-O bonds of the PO4 tetrahedra as well as vibrations of V-O bonds of the VO4 tetrahedra appeared. Analysis of Mid-IR spectra and Raman spectra also allowed observing correlation between the band positions and the extent of the anionic substitution among the studied series. The structure of pyromorphite and vanadinite is generally similar, although the two minerals vary in chemical composition. This variability results probably from the properties of individual ions.

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Modelowanie cyklu produkcyjnego przy użyciu techniki mapowania procesu

Topolska J.

Logistyka

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2014

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nr 6

PL

W przedsiębiorstwach reorganizacja procesu nie jest łatwym zadaniem, gdyż wymusza na osobach ją przeprowadzających spojrzenie na cały proces pod różnym kątem, z każdego możliwego punktu widzenia. Powoduje przez to ciągłe poszukiwanie nowych rozwiązań, które pozwoliłby osiągnąć zamierzony rezultat. W badaniach podjęto próbę przeorganizowania procesu produkcyjnego wykorzystując dane z przedsiębiorstwa, mapowanie całego procesu z uwzględnieniem wymagań klientów. Przeanalizowano rozbudowę stanowisk, dodatkowe zatrudnienie pod potrzeby zmiany cyklu pracy na linii produkcyjnej. Zmiany przedstawiono w postaci proponowanego stany w procesie mapowania. Reorganizacja procesu produkcyjnego pozwoli na utrzymanie stałych klientów w przedsiębiorstwie i pozyskanie nowych.

EN

The businesses reorganization process is not an easy task, since it forces people carrying look at the whole process from a different angle, from every possible point of view. This results in the constant search for new solutions that would achieve the desired result. The study attempted to reorganize the production process using data from the company, mapping the entire process taking into account the requirements of the customers. We analyzed the development of positions, additional employment for the needs of changes in the work on the production line. Changes are shown in the form of the proposed conditions in the mapping process. The reorganization of the production process will allow for the maintenance of regular customers in the enterprise and attracting new ones.

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Optimization of synthesis conditions of pyromorphite-vanadinite and mimetite-vanadinite solid solution series

Janicka U., Bajda T., Topolska J., Manecki M.

Geology, Geophysics and Environment

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2014

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Vol. 40, no. 1

88

EN

Minerals: pyromorphite Pb5(PO4)3Cl, mimetite Pb5(As04)3Cl and vanadinite Pb5(VO4)3Cl belong to the apatite supergroup. Commonly they form in hypergenic conditions. They are best known from the oxidation zones of lead ore deposits. Natural pyromorphite usually contains admixture of arse-nates or vanadates, whereas mimetite or vanadinite contain admixtures of phosphates. Solid solutions of the pyromorphite-mimetite series are well known, while the knowledge about anionie substitutions in vanadinite is incomplete. Therefore, the aim of this study was to find optimal conditions for the synthesis of pyromorphite-vanadinte and mimetite-vanadinite solid solution series. This research will allow to check the range of possible anionie substitutions, formation conditions such as pH, temperature and in, turn, to obtain better knowledge about the properties of these minerals. Pyromorphite, mimetite, vanadinite and pyromorphite-vanadinite and mimetite-vanadinite solid solutions series were synthesized from aqueous solutions. Solutions containing Pb2+, PO43-, AsO43-, VO3- , VO43- and Cl- ions in stoichiometric molar proportions were dropwise mixing. This method of synthesis allows controlling the stoichiometry of the chemical composition of synthetic precipitates. Synthesis reactions were carried out at various pH and at different temperatures (range from 25°C to 85°C). After the synthesis, suspensions were left for two weeks for aging. Then the suspensions were filtered using a Biichner funnel. The precipitates were washed with double-distilled water and acetone, and then dried. Synthetic precipitates were analyzed using various analytical techniques including X-Ray diffraction (XRD), Scanning electron microscopy coupled with Energy Dispersive Spectroscopy (SEM/EDS), Infrared absorption spectroscopy (FTIR) and Raman spectroscopy. Results of XRD, SEM/EDS, FTIR and Raman spectroscopy analyzes of studied samples showed that temperature 25°C and pH = 3.5 are optimal conditions to synthesize pyromorphite-vanadinite and mimetite-vanadinite solid solution series. Chervetite Pb2V2O7 was formed together with studied phases at lower pH values (1.7, 2.2), or higher temperatures (75°C, 85°C). At pH = 11.5, minerals with hydroxyl groups were formed. It has been observed that the formation of pyromorphite-vanadinite and mimetite-vanadinite solid solution series mainly depends on the pH values. The temperature is less important.

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The effect of gluconic acid secretion by phosphate-solubilizing Pseudomonas putida bacteria on dissolution of pyromorphite Pb5(PO4)3Cl and Pb remobilization

Topolska J., Borowicz P., Manecki M., Bajda T., Kaschabek S., Merkel B. J.

Annales Societatis Geologorum Poloniae

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2013

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Vol. 83, No. 4

343--351

EN

The purpose of this study was to investigate the effect of bacterially produced gluconic acid on the dissolution of pyromorphite and Pb remobilization. Pyromorphite Pb5(PO4)3Cl is formed as a product of the phosphate-induced treatment of Pb-contaminated sites. This very stable mineral greatly decreases the bioavailability of Pb. In this study, bacterial and abiotic batch experiments on the dissolution of pyromorphite were carried out. In the microbial experiments, the mineral was dissolved in the presence of the phosphate–solubilizing soil bacterium, Pseudomonas putida. The bacterial growth medium was supplemented with glucose, which under natural condi- tions can be supplied to microbes via symbiosis with plants. P. putida acquired P from pyromorphite and enhanced its dissolution. Elevated Pb concentrations were observed in the suspensions with bacteria. The bacterial secretion of 16.5 mM gluconic acid played a significant role in Pb remobilization; the pH of the solution dropped down from an initial 7.4 to 3.5. In the abiotic experiments, pyromorphite was dissolved at several concentrations of gluconic acid and at an acidic to neutral pH range. Both acidification and formation of stable Pb-gluconate ligands enhanced the dissolution of pyromorphite and caused Pb remobilization.