Resin-in-pulp method for uranium recovery from leached pulp of low grade uranium ore

An improved process for the separation of uranium from the leached pulp of low grade uranium ore is reported using the resin-in-pulp method. For this study, four small pachucas were designed and calibrated. A series of tests were conducted batch-wise to determine the optimum conditions for uranium adsorption on a strong base anion exchange resin. The particle size of resin was 0.6–1.6 mm and the particle size of pulp was − 0.1 mm. Flow rates of resin and pulp were adjusted on 10 ml/h and 1 ml/h, respectively. The redox potential of pulp was 500 mV and the pH of pulp was 1.8. A McCabe Thiele diagram was constructed for the process and the experimental results confirmed the theoretical predictions. It is concluded that four stage counter-current resin-in-pulp operation under optimum conditions is sufficient to recover about 99% of the uranium from the leached ore.     

Small cell experiments for electrolytic reduction of uranium oxides to uranium metal using fluoride salts

Electrolytic reduction of uranium oxide was proposed for the preparation of uranium metal feed for the atomic vapor laser isotope separation (AVLIS) process. A laboratory cell of 25-cm ID was operated to obtain additional information in areas important to design and operation of a pilot plant cell. Reproducible test results and useful operating and control procedures were demonstrated. About 20 kg of uranium metal of acceptable purity were prepared. A good supply of dissolved UO₂ feed at the anode is the most important controlling requirement for efficient cell operation. A large fraction of the cell current is “nonproductive” in that it does not produce a metal product nor consume carbon anodes. All useful test conditions gave some reduction of UF₄ to produce CF₄ in addition to the reduction of UO₂, but the fraction of metal from the reduction of UF₄ can be decreased by increasing the concentration of dissolved UO₂. Operation of large continuous cells would probably be limited to current efficiencies of less than 60 Pct, and more than 20 Pct of the metal would result from the reduction of UF₄.     

Production of fungal antigens from local strains for the immunodiagnosis of mycoses in Mexico

Allergic diseases caused by inhalant allergens are considered to be a major health problem. Allergic rhinitis, now affecting about 15% of the population, represents an inflammatory reaction, that may lead to asthma and chronic sinusitis as subsequent problems. Diagnosis should be based on a step-by-step concept, that also takes the clinical relevance of sensibilisations and other forms of nasal hyperreactivity into account. The aims of therapy are to limit the inflammatory reaction and to restore patient's quality of life. To achieve this goal, avoidance measures, immunotherapy and antiallergic drugs are currently used. The indication for and the performance of an immunotherapy demands special knowledge, and also the different drug activities and possible side effects should be thoroughly considered.     

Microbial extraction of nickel from Sukinda chromite overburden by Acidithiobacillus ferrooxidans and Aspergillus strains

In this study, the recovery of nickel from a low-grade chromite overburden was attempted by employing two fungal strains, Aspergillus niger and Aspergillus fumigatus, and a mixed culture of mesophilic acidophiles (predominantly Acidithiobacillus ferrooxidans). Various factors were studied for bioleaching of chromite overburden such as, temperature, pH and pulp density. It was found that the At. ferrooxidans culture solubilized nickel effectively at temperatures ranging from 30 °C to 37 °C, whereas the organism was not able to solubilize nickel at higher temperatures, such as 45 °C. The use of higher pulp density resulted in a decrease of the percent nickel recovery whereas lower pulp density resulted in higher recovery values. Besides, increased supplemental ferrous iron increased the leaching efficiency of the At. ferrooxidans culture. The maximum nickel solubilization was 40%, at 2% pulp density, and 24%, at 10% pulp density, at 30 °C after 28 days leaching at 150 rpm.In the case of fungal strains, a comparison of leach ability of chromite overburden and roasted overburden was made. The factors studied were pulp density and reaction time. The adapted fungal strain showed better leaching results as compared to the unadapted strains. The in situ nickel leaching efficiency of a laboratory stock culture of A. niger showed maximum recovery of 34% nickel with roasted chromite overburden, at 2% pulp density, while 32% nickel was solubilized by A. fumigatus, under the same conditions at 30 °C and 150 rpm, after 28 days incubation.     

Distribution of the fungal transposon Restless: full-length and truncated copies in closely related strains

We have investigated the changes in biochemical markers and in pyridinium cross-links in bone in hypophosphatemic rats. Six-week-old female Wistar rats were divided into two groups (normal diet and a phosphate-deficient diet) and fed for 8 weeks. A low phosphate intake caused a significant difference in the concentrations of osteocalcin and alkaline phosphatase with advancing rachitis as well as an increase in bone resorption marker concentrations in urine. Femur biochemical analysis revealed a significant (p < 0.005) increase in deoxypyridinoline per mole collagen in the phosphate-deficient group which suggested that urinary excretions of pyridinium cross-links might reflect not only bone resorption but also increased pyridinium cross-links in bone matrix collagen. Our results demonstrate that a low phosphate intake causes an increase of pyridinium cross-link formation as well as a discrepancy between the circulation levels of alkaline phosphatase and osteocalcin with advancing rachitis. These alterations induced by low phosphate intake should be considered when interpreting the values of biochemical markers.     

Strain hardening of copper single crystals at high strains and dynamical recovery processes

Single crystals of copper lere deformed by rolling at room temperature in tlo orientations. Different stress-strain characteristics lere found. In hard orientation (Rolling Plane ∥ (11̄1), Rolling Direction ∥ [1̄45]) a period of rapid strain hardening is folloled by the constancy of the flol stress. In soft orientation (Rolling Plane ∥ (3̄2̄1), Rolling Direction ∥ [1̄45]) a tlo-stage process of the strain hardening las found but no plateau of stress las observed up to strains of the order of three. On the basis of strain rate change and temperature change experiments and structural observations (optical and electron microscopes) tlo different mechanisms of dynamical recovery lere identified. In particular, a nel dynamical recovery process (D.R.t-2) las found to be the result of activation of the formally inactive slip direction. The intensity of this process in hard-oriented crystals leads to localilation of strain into lell-defined shear bands resulting in a plateau on the σ-ϵ curve.     

Exercise VO2 estimation using recovery sampling

Various situations present a challenge to determine oxygen uptake (VO2) accurately simply because of the restrictions imposed by the equipment employed. This investigation was undertaken to 1) compare a select number of recovery VO2 measurements with respect to their accuracy in estimating actual exercise VO2 and 2) to determine whether absolute workload or VO2max affect this relationship. Fifteen subjects [8 highly trained (HT), VO2max +/- SD = 70.2 +/- 3.5 ml/kg . min-1 and 7 untrained (UT), VO2max = 49.7 +/- 3.8 ml/kg . min-1] completed a number of 5 min workbouts on a bicycle ergometer at 25-70% VO2max (VO2 = .899--3.879 l . min-1). VO2 and VCO2 (l . min-1) were monitored continuously throughout the exercise and for 5 min of recovery via a breath-by-breath system. The results indicated that 1) exercise VO2 +/- Sy.x can be estimated from several recovery collection periods, the first breath y = .953X + .441 +/- .319, the first two breaths y = 1.046X + .327 +/- .270, the first three breaths y = 1.089X + .260 +/- .241, and the second three breaths y = 1.101X + .387 +/- .234, and 2) VO2max does not affect this relationship (p greater than 0.05) while increasing absolute workload produces a greater exercise VO2 underestimation (p less than 0.05). It was concluded that using this method exercise VO2 can be estimated with reasonable accuracy (Sy.x = .234--.319, r = .92--.94, p less than 0.01).     

An alternate process for the recovery of uranium by ion exchange: A study of the HIMIX process

An alternative approach to the recovery of uranium by ion exchange involves the additional loading of uranium onto a partially loaded resin followed by the elution of uranium from the more highly charged resin. The conditioning of the resin in this manner provides for the possible displacement of impurities from the resin and the production of an eluate suitable for the direct precipitation of yellowcake at a reduced consumption of eluant.This paper presents the results of pilot-plant and bench-scale experiments on the conditioning and elution steps. Variables such as the initial uranium concentration of the conditioning liquor, pH, temperature, and contact time were considered in the conditioning process together with the behaviour of thorium and iron impurities. In the elution work the effects of eluant flowrate, sulphuric acid concentration, elution temperature, and initial uranium loading on eluate uranium concentration and elution time were studied. The extent to which the further adsorption of uranium onto the resin together with thorium and iron displacement can be realized is indicated. In addition it is shown that an eluate suitable for yellowcake production can be obtained at an acid consumption significantly less than in the conventional processes.     

Transcatheter occlusion of native persistent ductus arteriosus using conventional Gianturco coils

Two hundred eleven patients with small- to moderate-sized native patent ductus arteriosus underwent closure using Gianturco coils, employing the transvenous multiple catheter approach. Short-term results showed a high rate of complete occlusion and a potential long-term complication of mild left pulmonary artery stenosis in a small number of patients.     

Elastographic dynamic range expansion using variable applied strains

In elastography, we want to image the entire range of stiffnesses of the elastic components found in inhomogeneous tissues. In order to achieve this, the elastographic dynamic range should equal the entire stiffness dynamic range in the target. Various sources of noise limit the dynamic range of elastography. The recently-defined strain filter concept offers an analytical and graphical way of observing these limitations. In this paper, we describe a method that achieves the expansion of the elastographic dynamic range. It involves the application of variable strains in combination with selective storage of strain data that have optimal elastographic signal-to-noise ratios. This expands the current dynamic range of elastography by orders of magnitude when compared to single compression elastography. The process is explained theoretically using the strain filter framework, and 1 D as well as 2D tissue simulations are used to corroborate the theory.     

Solvent extraction of uranium from dilute solutions using a gas-bubble mixed extraction column

A modified solvent extraction process for recovering uranium from very dilute solutions, such as mine waters or copper dump liquors, has been developed and tested on a laboratory scale. The system utilizes a column in which the aqueous feed flows downward through a liquid organic extractant. A countercurrent flow of gas is used to achieve mixing and enhance mass transfer. Acid sulfate solutions at pH 1.5 containing either 0.010 or 0.015 g/1 U₃O₈ comprised the feed. The extractant used was Alamine® 336 dissolved in fuel oil. Critical parameters of the system, such as length to diameter ratio of the organic phase, volume ratio of aqueous to organic in the column, and flow rates of aqueous feed and gas are examined.     

Gold recovery from dilute gold solutions using DEAE-cellulose

The present work investigates gold recovery using DEAE-cellulose, a common biopolymer derivative, from synthetically prepared diluted gold-bearing solutions of 50 ppm. The effects of different recovery parameters on gold recovery efficiency were studied in detail. It was demonstrated that gold recovery efficiency increased with an increasing amount of sorbent, as well as increasing contact time. A gold recovery efficiency of 99% was attained under conditions of 20–40 g DEAE-cellulose per liter at a shaking rate of 130 rpm for 30 min at room temperature. On the other hand, with smaller amounts of sorbent (6 g/l), it was also possible to recover gold from the solution with 99% efficiency when the reaction temperature was increased to 60 °C. The shaking rate and temperature were demonstrated to play a vital role in the recovery process. It was also found that gold recovery by DEAE-cellulose is an intermediate-controlled process with an activation energy of 37.11 kJ/mol. The XRD pattern and SEM images revealed that the recovered gold was in the metallic form.     

酸性含汞溶液中电沉积回收汞的研究

针对有色金属冶炼烟气中湿法脱汞过程产生的硫脲汞溶液难处置的问题,研究提出了电沉积从硫脲汞溶液中回收汞的新工艺.采用线性电位扫描法得到汞电沉积过程的阴极极化曲线,考察了不同杂质离子对硫脲汞溶液阴极极化曲线的影响.结果显示,在控制阴极电位为-0.55～-0.45 V的条件下,溶液中的汞可选择性沉积,溶液中Fe~(3+)、Cu~(2+)和H_2SO_3并不会影响溶液中汞的电沉积,即汞选择性电沉积的电位为-0.55～-0.45 V.采用控电位技术对硫脲汞溶液电解回收汞工艺进行研究,探究了电解质种类和浓度、电解液温度、搅拌速率、电解时间等因素对汞回收效率的影响.得到在阴极材料为铜片的条件下,最佳的电解工艺参数:电解质为0.24 mol·L~(-1) Na_2SO_4,电解液温度为30～40℃,搅拌速度为100～300 r·min~(-1),SO_3~(2-)浓度为8 mmol·L~(-1),电解时间为5 h.最佳工艺条件下,溶液中汞的回收效率可达98%以上.对阴极电解产物进行分析,阴极上的汞为单质汞,且纯度超过99%.     

Ferric nitrate leaching of uranium and radium from uranium ores

A dilute aqueous acidic ferric nitrate solution of a relatively low concentration of 0.02 M is found to remove up to 97% of the uranium and 93% radium from ores occurring in the Elliot Lake area of Canada, after an initial flotation-separation of the sulfide minerals from the ore. A temperature of 75°C, a contact time of 24 h and a liquid/solid ratio of 1 ml/g are found optimum for leaching giving tailings which are effectively sulfide-free and with radium levels approaching a low value of 25 pCi/g. Radium may be removed from the leachate by adsorption and uranium by solvent extraction. An amount of 80–87% of the ferric nitrate may be recirculated for further leaching. Because of the low reagent concentrations and the recycle, it is possible to keep nitrate ion levels in the effluent below the prescribed level of 10 mg/l.     

Detection of tetracycline- and erythromycin-resistant urogenital Mycoplasma strains using PCR

The use of PCR made it possible to obtain data on the occurrence of genital mycoplasms in subjects with different pathological states of their urogenital system. The detection rate of U.urealyticum was 10.7-25.1% in males and 23.0-61.9% in females. The detection rate of Mycoplasma hominis was 6.2-11.4% in males and 3.8-22.9% in females. The detection rate of M.genitalium was 6.2-29.6% in males and 4.7-30.0% in females. The study carried out by means of amplification test systems for the detection of genes controlling resistance to tetracycline (tet-M and tet-O) and to erythromycin (erm) demonstrated that U.urealyticum contained the tet-determinant in 60% of cases and M.hominis, in 57.14% of cases. As revealed with the use of PCR techniques, the occurrence of erythromycin-resistant Ureaplasma strains was not high and was equal to 2.1%.     

Functional dissection of systemic lupus erythematosus using congenic mouse strains

We describe the in vivo phenotypes associated with three genomic intervals containing systemic lupus erythematosus (SLE)-susceptibility genes derived from the SLE-prone NZM2410 strain on a C57BL/6 genome. These intervals were identified previously via a genome-wide analysis of SLE susceptibility in a (NZM2410 x C57BL/6)F1 x NZM2410 backcross, and transferred independently on a C57BL/6 background to produce three congenic strains: B6.NZMc1 carrying Sle1, B6.NZMc4 carrying Sle2, and B6.NZMc7 carrying Sle3. B6.NZMc1 develops high titers of IgG anti-nuclear autoantibodies in the absence of any severe nephritis. B6.NZMc4 spontaneously develops elevated levels of IgM, but not IgG Abs against several Ags, indicative of polyclonal activation or polyreactivity affecting the B cell lineage. B6.NZMc7 causes the production of IgM and IgG Abs against both nuclear and non-nuclear Ags and the development of severe lupus nephritis. Therefore, our results show that three defined genomic intervals from the NZM2410 SLE-prone strain each contribute specific component phenotypes that have been associated with SLE, which in combination can mediate severe disease.