Anaerobic, Nitrate-Dependent Oxidation of Uraninite by the Chemolithoautotroph Thiobacillus denitrificans: Cell Suspension and Whole-Genome Transcriptional Studies (original) (raw)
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An Overview of Calcite Recovery by Flotation
Materials Circular Economy, 2020
In general, precipitated calcium carbonate (PCC) is used as a mineral filler in paper industries; while natural calcite (CaCO3) ore is also suitable for industrial use if it is a finely ground high-grade material. Naturally, calcite is found in the form of high- or low-grade ores and it is one of the most widely distributed industrial minerals on the earth’s crust. However, it is rarely found in its pure form and is generally associated with other gangue minerals; the type and percentage of which vary from one deposit to another. These minerals are generally separated by flotation and/or magnetic separation (in the case of iron impurities). Calcite ores typically contain metal sulphide, silicate, or other calcium-containing impurity minerals, which can be removed by flotation. A tremendous amount of research has been performed on refining the flotation process for calcite ores and designing the reagents (specifically, collectors) to increase the efficiency of the process. Metal sulp...
Comparative studies of two cationic collectors in the flotation of pyrolusite and calcite
International Journal of Mineral Processing, 2017
The collecting ability of Dodecylamine (DDA) and Dodecyltrimethylammonium chloride (DTAC) as two cationic collectors was investigated in the flotation of pyrolusite and calcite by carrying out the flotation experiments, FTIR analysis, zeta potential tests and contact angle measurements. The single mineral flotation experiments show that the maximum differences between the floatability of pyrolusite and calcite occurring at a pH of 7.5 in the presence of DTAC is more than that of DDA. This means that DTAC acts more selectively than the DDA collector. In the microflotation experiments carried out on the artificially mixed minerals, the MnO content and recovery in the pyrolusite concentrate obtained by DDA collector is greater than that achieved by DTAC. As evidenced by ore flotation results and contact angle measurements, in the presence of both collectors, sodium carbonate acts more effective than calcium chloride as calcite depressant agents. In the ore flotation experiments, a pyrolusite concentrate containing higher MnO grade and recovery is obtained using DDA collector in comparison with DTAC. These results indicate that the collecting power of DDA is significantly more than DTAC collector. FTIR analysis and zeta potential tests show that both collectors adsorb on the surface of pyrolusite and calcite through the electrostatic interactions. Also, these analyses indicate that the adsorption of DDA on the surface of both minerals is greater and stronger than that of the DTAC collector.
Transactions of Nonferrous Metals Society of China, 2017
In the cationic flotation of pyrolusite using dodecyl ammine (DDA), the depressive effect of sodium carbonate and calcium chloride on the calcite mineral was investigated systematically through flotation experiments, FTIR analysis, contact angle measurements and zeta potential tests. The microflotation experiments showed that both depressant agents decrease the flotation recovery of calcite significantly. In addition, sodium carbonate acts as activator agent for pyrolusite, and increases its floatability. The flotation experiments and contact angle measurements indicated that the selective depression effect of sodium carbonate on the calcite mineral is more than that of calcium chloride. As evidenced by zeta potential and FT-IR analysis, sodium carbonate decreases the negative charges on the surface of calcite mineral and subsequently reduces the adsorption of DDA collector through electrostatic forces. At a pH of 7.5, using 2000 g/t DDA and 1500 g/t sodium carbonate, a pyrolusite concentrate containing almost 40% MnO with 71.5% recovery is achieved by carrying out the ore flotation experiments on the tabling pre-concentrate.
The effect of reagents on selective flotation of smithsonite–calcite–quartz
Minerals Engineering, 2009
In this paper the effects of sodium sulphide, sodium hexa methaphosphate (SH), sodium fluoric, starch and sodium silicate adsorption on smithsonite, quartz and calcite surfaces at various pH values, and using Armac C and oleic acid as collectors were investigated through microflotation. Also, the effects of various primary amine collectors (Armac C, Armac T, Flotigam SA, Flotigam TA and Armeen TD) were investigated for smithsonite flotation. The flotation tests were performed using purified samples from Angooran mine by the microflotation technique. The cationic flotation results showed that the maximum recovery of smithsonite could be improved to 92% using 400 g/t Armac C and 500 g/t sodium sulphide at pH 11. Also, the quartz and calcite recoveries reached 98% and 89%, respectively, at the above mentioned conditions. Moreover, using 1250 g/t SH and 1500 g/t sodium silicate as a depressant, the quartz and calcite recoveries decreased to 70% and 20%, respectively, and also the smithsonite recovery was reduced to 82%. Furthermore, the experiments showed that the behavior of sodium fluoric as a quartz depressant is similar to that of sodium silicate. Flotation results using oleic acid revealed that the maximum recovery of 90% occurs at pH 9 and 500 g/t oleic acid. Also, the quartz and calcite recoveries reached 26% and 87%, respectively, in the anionic flotation conditions. Increasing amount of sodium silicate to 2000 g/t caused a decrease in the smithsonite recovery to 87% and also decreased the calcite and quartz recoveries by 10% and 15%, respectively.
A Review of the Flotation of Copper Minerals
International Journal of Sciences: Basic and Applied Research, 2017
Copper is most commonly present in the earth's crust as copper-iron-sulphide and copper sulphide minerals, for example, chalcopyrite (CuFeS 2), bornite (Cu 5 FeS 4) and chalcocite (Cu 2 S). Copper also occurs to a lesser extent in oxidised minerals, for instance, malachite (Cu 2 (OH)CO 3), azurite (Cu 3 (OH) 2 (CO 3) 2) and chrysocolla (CuO.SiO₂). These oxidised copper minerals are found in weathered regions of most copper sulphide ore bodies The overlaying oxidic ore is usually stockpiled after it is removed from the sulphide lode and left unprocessed as the sulphide ore is simpler to recover by conventional flotation procedures and thus, more attractive to the plant operator. Oxidic ore can be concentrated using flotation or, if it has a low acid demand, it may be economic to acid heap leach the stockpile. The recovery of these copper minerals by flotation or hydrometallurgy from ores, typically containing 0.5%TCu (open pit mines) and 1-2%TCu (underground mines) is of great commercial importance. This paper reviews the literature on the recovery of the above mentioned minerals by flotation. The increasing complexity of ore deposits, declining ore grades and higher global demand for copper has resulted in increased ore processing by flotation plants around the world. The depletion of highgrade ores, increased demand for metals and separation difficulties associated with low-grade or refractory ores, has resulted in new flotation challenges in terms of economic and sustainable beneficiation of these ores. However, improvements in technology have allowed various processing plants to treat low-grade ores at almost no extra cost.
Minerals Engineering, 2014
The amenability of a low-grade Egyptian phosphorite to flotation for separation of both calcareous and siliceous gangue minerals by just pH control was investigated. The ore, assaying 19.39% P 2 O 5 , 16.1% L.O.I. and 12.41% A.I. is mainly composed of francolite and hydroxy apatite minerals consolidated into three different phosphatic varieties according to texture and origin, i.e. coarse phospho-chem, sharpedged phospho-clast and fine cementing phospho-mud. This was endorsed by microscopic investigation of thin sections. X-ray diffraction analysis of the ore sample showed that the main gangue minerals are calcite and quartz with minor dolomite and some gypsum.
Selective flotation of calcium minerals using double-headed collectors
Journal of Dispersion Science and Technology
A study was performed involving a series of double-headed carboxylate collectors with varying distance between the head groups (one, two or three carbon atoms). A collector with the same alkyl chain length but with only one carboxylate group was also included. All these were aminoacid based amphiphiles and the polar head group was connected to the hydrophobic tail via an amide linkage. Selective flotation recovery of different calcium minerals using these collectors was investigated. The double-headed collector with one carbon atom between the carboxylate groups was an apatite and fluorite specific reagent while the monocarboxylate surfactant showed high specificity for calcite. The flotation behavior of a simple conventional collector of the same alkyl chain length, a fatty acid salt, was also determined under identical flotation conditions in order to understand the effect of the amide group. Complementary experiments (f potential measurements, adsorption isotherm determinations) were also performed for these reagents. In order to shed light on the selectivity obtained with the dicarboxylate surfactants, the distances between the head groups were calculated and compared with the distances between neighboring calcium atoms on the surface of the minerals. It was found that the high degree of selectivity could be rationalized by perfect matching of these distances. To the best of our knowledge this is the first study where flotation selectivity in complex calcium mineral systems has been explained in terms of molecular recognition governing the interaction between the collector and the mineral surface.
FLOTATION ROUTES FOR A PHOSPHATE ORE BEARING SILICATE-CARBONATE GANGUE
This laboratory scale investigation addressed two different process routes for the concentration of a phosphate ore bearing a silicate-carbonate gangue: (i) bulk apatite and calcite flotation followed by calcite flotation in the presence of phosphoric and citric acids; (ii) calcite flotation in the presence of carbon dioxide followed by apatite flotation. The target of selectively separating apatite from the contaminating silicates and carbonates was achieved. Following the flotation experiments, calcite zeta potential determinations were performed aiming at clarifying the mechanisms that rule the adsorption of the soybean bran oil soap onto the mineral surface in the presence of the modifying agents phosphoric acid, citric acid, and carbon dioxide.
A Collector Promoter for Apatite Flotation in the Serra do Salitre Complex
Minerals
The concern about enhancing the productivity of Salitre phosphate mines has led to an extensive research and development program on new reagents, aimed at the sustainable processing of the ore, with greater production of phosphate concentrate and, consequently, less waste disposal in the tailings dam. Flotation is the most widely applied technique for processing of phosphate rocks, using mainly fatty acids and their salts as collectors. In partnership with BASF Mining Solutions, a new collector system was developed based on soy oil fatty acid (SOFA) and BASF’s co-collector Lupromin® FP A 1210 Base (L.1210, a mix of synthetic surfactants). The laboratory scale flotation results showed that most effective performance was achieved with a ratio SOFA:L.1210 of 70:30, while in the industrial application the ideal proportion was 90:10. This difference in reagent ratio is directly related to the surface tension of the bulk, making the apatite more or less hydrophobic, directly affecting the...
Physicochemical Problems of Mineral Processing, 2018
Mica and heavy minerals containing iron oxides and titanium oxides such as rutile and sphene are floated using cationic and anionic collectors, respectively. In this study, separation of colored impurities including mica and heavy minerals from the albite ore obtained from the Aydin region in Turkey was investigated by multi-stage flotation. The effects of the new cationic and various anionic collectors and their dosages in either acidic or natural circuits were investigated to upgrade the albite ore. In the case of the flotation stage of mica minerals, the results obtained from this study showed that the stearylamine collector (Flotigam-S) gave the best performance and an albite concentrate with 7.58% Na 2 O grade was produced with 81.40% Na 2 O recovery at 400 g/Mg Flotigam-S under the acidic condition at pH 3. Additionally, in the heavy minerals flotation stage, the use of Naoleate in the natural circuit (pH 6) was the most effective for removal of iron and titanium oxides, and an albite concentrate with 0.042% Fe 2 O 3 and 0.061% TiO 2 grades was produced with 91.89% Fe 2 O 3 and 88.56 %TiO 2 recoveries, respectively, with the use of 900 g/Mg Na-oleate. Under the optimum conditions, the colored impurities containing mica minerals, iron oxides and particularly sphene as well as rutile could be effectively removed from the albite ore in the presence of Flotigam-S and Naoleate collectors by multi-stage flotation.