Removal of iron from sandstone by magnetic separation and leaching: case of El-Aouana deposit (Algeria)

To improve the quality of raw materials from North East Algeria and their application in the field of flat glass manufacturing, the sandstone of El-Aouana (Jijel) was subjected to a physicochemical characterization. Analysis techniques such as X-ray diffraction, atomic absorption spectrophotometry and a chemical analysis of size fractions by sieving were used. According to this characterization it is noticed that sandstone feedstock contains primarily quartz (SiO2), as well as ferriferous minerals considered as impurities during glass manufacturing. This work concerns the removal of iron oxide from silica sandstone to obtain a material acceptable for flat glass manufacturing. For this, we have studied the silica enrichment process using a magnetic separation. Moreover, a leaching process by using hydrochloric acid has been studied under various experimental conditions; the parameters studied were: hydrochloric concentration, temperature, and time of contact. The results obtained show that the leaching studied presents a better removal of iron oxide after 150 min of treatment at temperature 90°C with a 3 mol/L, a concentrate obtained final of 99.16% SiO2 with a content of 0.01% Fe2O3

Recycling of siliceous by-products to reduce their impacts on the environment

Currently, there is a tendency to use less silica rich ores given the depletion of high-quality resources. The raw kaolin treatment of Tamazert (Eastern Algeria) produces, by hydrocyclone process, approximately 80 % of siliceous by-products. These siliceous wastes, which are stored in the open air, constitute a significant environmental problem. This research work aims to improve the quality of siliceous by-products, more particularly, to a process for the elimination of iron oxides and aluminum to make this raw material usable industrially as well as solving environmental issues. The collected by-products, were characterized by different techniques, such as X-ray fluorescence (XRF) and X-ray diffraction (XRD). XRF confirmed that the by-products east siliceous, with content going up to 82 % of SiO2. The by-product resulted from the raw kaolin treatment, mainly contains varying amounts of impurities such as iron oxide, titanium oxide and alumina. In all cases, the presence of these impurities affects the color and the physical properties of the mineral, and so lowers the economic value and limits the industrial application. In this framework, the classified fraction (–500)–(+100) µm was directed to attrition scrubbing followed by magnetic separation technique and chemical treatment by sulphuric acid with different concentrations. The results of the beneficiation tests of by-product indicate that using the attrition scrubbing alone not provides a suitable product for glass manufacture. The magnetic separation was tested with attrition on the useful fraction ((–500)–(+100) μm). The non-magnetic attritional fraction concentrates less than 0.45 % of Al2O3 and 0.05 % of Fe2O3. This low content coupled with a remarkable percentage in silica of 97.98 %.The tests by attrition and leaching with 40 % of sulphuric acid show, on the one hand, significant results with a high percentage of silica (>98.5 %) against 0.04 % Fe2O3 and 0.66 % Al2O3 ,and on the other hand, that the enriched product meets the standards required by glass making

Rilpivirine in HIV-1-positive women initiating pregnancy: to switch or not to switch?

International audienceBackgroundSafety data about rilpivirine use during pregnancy remain scarce, and rilpivirine plasma concentrations are reduced during second/third trimesters, with a potential risk of viral breakthroughs. Thus, French guidelines recommend switching to rilpivirine-free combinations (RFCs) during pregnancy.ObjectivesTo describe the characteristics of women initiating pregnancy while on rilpivirine and to compare the outcomes for virologically suppressed subjects continuing rilpivirine until delivery versus switching to an RFC.MethodsIn the ANRS-EPF French Perinatal cohort, we included women on rilpivirine at conception in 2010–18. Pregnancy outcomes were compared between patients continuing versus interrupting rilpivirine. In women with documented viral suppression (<50 copies/mL) before 14 weeks of gestation (WG) while on rilpivirine, we compared the probability of viral rebound (≥50 copies/mL) during pregnancy between subjects continuing rilpivirine versus those switching to RFC.ResultsAmong 247 women included, 88.7% had viral suppression at the beginning of pregnancy. Overall, 184 women (74.5%) switched to an RFC (mostly PI/ritonavir-based regimens) at a median gestational age of 8.0 WG. Plasma HIV-1 RNA nearest delivery was <50 copies/mL in 95.6% of women. Among 69 women with documented viral suppression before 14 WG, the risk of viral rebound was higher when switching to RFCs than when continuing rilpivirine (20.0% versus 0.0%, P = 0.046). Delivery outcomes were similar between groups (overall birth defects, 3.8/100 live births; pregnancy losses, 2.0%; preterm deliveries, 10.6%). No HIV transmission occurred.ConclusionsIn virologically suppressed women initiating pregnancy, continuing rilpivirine was associated with better virological outcome than changing regimen. We did not observe a higher risk of adverse pregnancy outcomes