Effect of Size-Distribution Environment on Breakage Parameters Using Closed-Cycle Grinding Tests.

The so-called population balance model (PBM) is the most widely used approach to describe the grinding process. The analysis of the grinding data is carried out using-among others-the one-size fraction BII method. According to the BII method, the breakage parameters can be determined when a narrow particle size fraction is used as feed material to the mill. However, it is commonly accepted that these parameters are influenced by changing the particle size distribution in the mill. Thus, this study examines the breakage parameters through kinetic testing in different natural-size distribution environments generated by closed-cycle grinding tests that simulate industrial milling conditions. The differentiation of the milling environments was accomplished using various reference sieves in the closed-cycle tests. The experimentally determined breakage parameters were back-calculated and then used to simulate the closed-cycle tests using the MODSIMTM software. Additionally, the energy efficiency was evaluated based on the specific surface area of the grinding products and the energy consumption. The results of the kinetic tests showed that the breakage rate of the coarse particles increases as the aperture size of the reference sieve decreases, and consequently, the content of fines in the mill increases. The back-calculated breakage parameters can be reliably used to simulate closed-cycle circuits, thus helping control industrial milling operations.

A novel and greener sequential column leaching approach for the treatment of two different Greek laterites.

Τhe present study investigates, from an environmental protection viewpoint, the efficiency of sequential column leaching of two different Greek laterites, i.e. a limonitic ore from central and a saprolitic ore from northern Greece. First, the most refractory limonitic laterite is leached in the first column for 15 days and the obtained pregnant leach solution (PLS) is further used for the leaching of the easier to treat saprolitic ore in the second column, thus achieving a significantly reduced acid consumption. The main parameters affecting the process efficiency, i.e. acid molarity (1.5 or 3 mol/L H2SO4) and addition of sodium sulfite (Na2SO3) in the leaching solution were studied. The extraction of Ni, Co, Fe, Al, Mg, Mn and Ca was determined by Atomic Absorption Spectroscopy (AAS), while the characterization of the ores and final residues was carried out by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA/DTA), and Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM-EDS) analysis. The results confirm the efficiency of the proposed green approach, which with the use of leaching solution containing 1.5 mol/L H2SO4 and 20 g/L Na2SO3 resulted in 73.8 % Ni, 71.6 % Co and 8.4 % Fe extraction after a short period of time (33 days), while the acid consumption, which is a serious environmental concern, was very low and did not exceed 300 kg/t ore. Overall, the proposed process not only improves the efficiency of leaching of different types of laterites for the recovery of both Ni and Co but also reduces the environmental impacts due to the significantly lower acid consumption.

Factors affecting co-valorization of fayalitic and ferronickel slags for the production of alkali activated materials.

The first objective of this experimental study is the assessment of the alkali activation potential of two types of fayalitic slags, an as-received one (FS) and the one obtained after plasma treatment (FSP) of the initial FS, for the production of alkali activated materials (AAMs). Furthermore, the second objective is the elucidation of the co-valorization potential of FS and FSP slags when mixed with ferronickel (FeNi) slag (LS). The alkaline activating solution used was a mixture of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). The effect of various operating parameters, such as H2O/Na2O and SiO2/Na2O ratios present in the activating solution, curing temperature, curing period and ageing period on the compressive strength, density, water adsorption, porosity and toxicity of the produced AAMs was explored. The structural integrity of selected AAMs was investigated after firing specimens for 6 h at temperature up to 500 °C, immersion in distilled water and acidic solution or subjection to freeze-thaw cycles for a period of 7 or 30 days. The results of this study show that FS- and FSP-based AAMs acquire compressive strength of 44.8 MPa and 27.2 MPa, respectively. When FS and FSP were mixed with LS at 50:50%wt ratios the compressive strength of the produced specimens increased to 64.3 MPa and 45.8 MPa, respectively. Furthermore, selected AAMs produced after co-valorisation of slags retained sufficient compressive strength after firing at 500 °C, 45-68 MPa, and exhibited very low toxicity. These findings prove the alkali activation potential of fayalitic slags as well as their co-valorization with ferronickel slag for the production of AAMs, an approach which is in line with the principles of zero-waste and circular economy.

A Successful Pregnancy Despite the Presence of an Intrauterine Fetal Bone Fragment.

OBJECTIVE: Intrauterine retention of fetal bones following a termination of a pregnancy is a rare complication. Among the few reported cases in literature, there has been no report describing the birth of a live fetus, despite the presence of an embryonic ossicle within the endometrial cavity. CASE REPORT: A 28-year-old woman, with an obstetrical history of a miscarriage at the 19th week of gestation, underwent a diagnostic hysteroscopy for evaluation of pelvic pain and infertility, which revealed an intrauterine embryonic ossicle. The patient did not comply with our recommendations to undergo a surgical hysteroscopy. The patient's next visit was during her 9th week of gestation. She was followed up regularly at our Obstetrics Department. Her gestation was uneventful, while an elective caesarean section at the 39th week of gestation was performed. CONCLUSION: The present clinical case has demonstrated that achieving childbearing is possible, despite the requirement of removing such bone fragments.

Large cyst of the vaginal wall in pregnancy.

Large vaginal cysts during pregnancy are rare and can mislead Obstetricians to a false diagnosis, that of "Protruding membranes". Aspiration of the cyst can be easily performed, resulting in the collapsing of the cyst and an uneventful vaginal delivery can be conducted.

Column leaching of low-grade saprolitic laterites and valorization of leaching residues.

Socio-economic data on nickel and cobalt show their importance throughout the entire metal value chain, from mining to end use, disposal and recycling. Thus, the extraction of both metals from primary and secondary raw materials as well as from wastes is currently considered strategically important for the industry and the society. In this paper heap leaching of Greek low-grade saprolitic laterites, with Ni content 0.97%, was investigated. The main parameters studied involved the strength of the H2SO4 solution used (49 and 147gL-1) and the effect of adding sodium sulfite (Na2SO3) in the leaching medium. The pregnant leach solution (PLS) was recycled several times during leaching in order to minimize acid consumption. The experimental results showed that within a period of 25days, and under the optimum conditions (147gL-1 H2SO4 and 20gL-1 Na2SO3), i) Ni and Co extractions were 72.5% and 47.4%, respectively and ii) Fe and Al co-extractions were 8.7% and 31.3%, respectively. Furthermore, valorization of the leaching residues through alkali activation using NaOH and Na2SiO3 and the addition of metakaolin (MK) for the production of inorganic polymers (IPs) was explored. X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Differential scanning calorimetry (DSC/TG) and Scanning electron microscopy (SEM-EDS) were used to characterize the ore, its leaching residues and the IPs. The IPs produced demonstrated high compressive strength, almost 40MPa and are suitable for a wide range of applications in the construction sector.

Pemphigoid gestationis.

Pemphigoid gestationis is a rare autoimmune skin disorder emerging exclusively during pregnancy. Topical and oral glucocorticoids as well as oral antihistamines are the standard medications administered during pregnancy, aiming to relieve pruritus and to suppress extensive blister formation. Obstetricians should be able to recognize and treat this rare clinical condition accordingly.

Screening for unknown mutations by a bioluminescent protein truncation test with homogeneous detection.

The protein truncation test (PTT) is important in screening for unknown mutations that cause premature termination of mRNA translation. PTT involves amplification of the interrogated sequence, in vitro transcription/translation, separation of the generated polypeptides, and detection. In this article, we report a bioluminescent protein truncation test, in which the detection of the nascent protein is performed directly in the expression mixture, within seconds, without the need for separation and purification. A DNA fragment encoding apoaequorin is fused, in-frame, downstream of the interrogated sequence. The fusion product is subjected to in vitro, coupled transcription and translation in the presence of coelenterazine. A wild-type DNA template allows translation to continue after the 3' end of the interrogated sequence, producing a chimeric protein whose C-terminal domain is the photoprotein aequorin. Aequorin is detected, with a high sensitivity, by its characteristic Ca(2+)-triggered, flash-type bioluminescent reaction. Active photoprotein is not produced when a truncating mutation is present in the interrogated sequence. As a model, the method was applied to the detection of truncating mutations in the APC gene (adenomatous polyposis coli).