Effect of hydraulic retention time and pH on oxidation of ferrous iron in simulated ferruginous acid mine drainage treatment with inoculation of iron-oxidizing bacteria

The effect of hydraulic retention time (HRT) and pH on the biooxidation of ferrous iron during simulated acid mine drainage (AMD) treatment was investigated.The simulated AMD was highly acidic (pH 2.5), rich in iron (about 1700 mg/L) and copper (about 200 mg/L), and contained high concentrations of sulfate (about 4700 mg/L).The biooxidation of ferrous iron was studied in a laboratory-scale upflow packed bed bioreactor (PBR).The HRT was shortened stepwise from 40 h to 20 h, 13 h, and 8 h under the acidic environment at a pH value of 2.2.Then, the influent pH value was changed from 2.2 to 1.2 at a constant suitable HRT.Physiochemical and microbial community structure analyses were performed on water samples and stuffing collected from the bioreactor under different conditions.The results indicate that the efficiency of ferrous iron oxidation gradually decreased with the decrease of HRT, and when the HRT exceeded 13 h, ferrous iron in AMD was almost completely oxidized.In addition, the best efficiency of ferrous iron oxidation was achieved at the influent pH value of 1.8.Microbial community structure analyses show that Leptospirillum is the predominant genus attached in the bioreactor, and low influent pH values are suitable for the growth of Leptospirillum.

Reduction Rate of Ferrous Oxide in Smelting Reduction

Reduction rate of ferrous oxide in smelting reduction with iron bath has been studied.The main affecting factors on reduction rate,such as composition of the melt,temperature of molten bath,basicity of slag and the way of supplying carbonaceous materials have also been investigated.

A critical review on the chemical wear and wear suppression of diamond tools in diamond cutting of ferrous metals

Diamond tools play a critical role in ultra-precision machining due to their excellent physical and mechanical material properties,such as that cutting edge can be sharpened to nanoscale accuracy.However,abrasive chemical reactions between diamond and non-diamond-machinable metal elements,including Fe,Cr,Ti,Ni,etc,can cause excessive tool wear in diamond cutting of such metals and most of their alloys.This paper reviews the latest achievements in the chemical wear and wear suppression methods for diamond tools in cutting of ferrous metals.The focus will be on the wear mechanism of diamond tools,and the typical wear reduction methods for diamond cutting of ferrous metals,including ultrasonic vibration cutting,cryogenic cutting,surface nitridation and plasma assisted cutting,etc.Relevant commercially available devices are introduced as well.Furthermore,future research trends in diamond tool wear suppression are discussed and examined.

Efficacy and Compliance of Oral Iron Poly-Maltose Complex versus Oral Ferrous Sulfate in the Treatment of Iron Deficiency Anemia in Pregnant Women

Objective: To compare the efficacy and compliance of the conventional therapy of iron deficiency anemia (ferrous sulfate) with the new forms of therapy chewable iron tablets: (iron polymaltose complex) in the treatment of iron deficiency anemia in pregnant women. Methods: This Randomized Control Trial study included 290 pregnant women with iron deficiency anemia, and they were randomly allocated to a control group who received ferrous sulfate capsules for two months and study group who received iron polymaltose complex chewable tablets for two months. Complete Blood Picture (hemoglobin level and hematocrit level) and Serum ferritin level were done after four and eight weeks to determine the efficacy. In addition, any complains or side effects had been reported to assess the tolerability of the drugs. Two-factor repeated-measures analysis of variance (ANOVA) was used to compare the change in hemoglobin and serum ferritin levels in both groups. Results: There was no statistical significant difference between the two research groups as regards baseline hemoglobin, and at week 4 from onset of treatment (p values = 0.990, 0.112, consecutively). However, there was statistical significant difference on week 8 of continuous drug intake in both groups in which the iron poly maltose complex research group had significantly higher hemoglobin levels (p value = 0.006). Conclusion: The results of the study showed oral iron polymaltose complex increases Hemoglobin and serum ferritin levels more than oral ferrous sulfate and produces less adverse effects than ferrous sulfate.

Enrichment of Phosphate on Ferrous Iron Phases during Bio-Reduction of Ferrihydrite

The reduction of less stable ferric hydroxides and formation of ferrous phases is critical for the fate of phosphorus in anaerobic soils and sediments. The interaction between ferrous iron and phosphate was investigated experimentally during the reduction of synthetic ferrihydrite with natural organic materials as carbon source. Ferrihydrite was readily reduced by dissimilatory iron reducing bacteria (DIRB) with between 52% and 73% Fe(III) converted to Fe(II) after 31 days, higher than without DIRB. Formation of ferrous phases was linearly coupled to almost complete removal of both aqueous and exchangeable phosphate. Simple model calculations based on the incubation data suggested ferrous phases bound phosphate with a molar ratio of Fe(II):P between 1.14 - 2.25 or a capacity of 246 - 485 mg·P·g-1 Fe(II). XRD analysis indicated that the ratio of Fe(II): P was responsible for the precipitation of vivianite (Fe3(PO4)2·8H2O), a dominant Fe(II) phosphate mineral in incubation systems. When the ratio of Fe(II):P was more than 1.5, the precipitation of Fe(II) phosphate was soundly crystallized to vivianite. Thus, reduction of ferric iron provides a mechanism for the further removal of available phosphate via the production of ferrous phases, with anaerobic soils and sediments potentially exhibiting a higher capacity to bind phosphate than some aerobic systems.

Influence of Ferric and Ferrous Iron on Chemical and Bacterial Leaching of Copper Flotation Concentrates

The effects of ferrous and ferric iron as well as redox potential on copper and iron extraction from the copper flotation concentrate of Sarcheshmeh, Kerman, Iran, were evaluated using shake flask leaching examinations. Experiments were carried out in the presence and absence of a mixed culture of moderately thermophile microorganisms at 50?C. Chemical leaching experiments were performed in the absence and presence of 0.15 M iron (ferric added medium, ferrous added medium and a mixture medium regulated at 420 mV, Pt. vs. Ag/AgCl). In addition, bioleaching experiments were carried out in the presence and absence of 0.1 M iron (ferric and ferrous added mediua) at pulp density 10% (w/v), inoculated bacteria 20% (v/v), initial pH 1.6, nutrient medium Norris and yeast extract addition 0.02% (w/w). Abiotic leaching tests showed that the addition of iron at low solution redox potentials significantly increased the rate and extent of copper dissolution but when ferric iron was added, despite a higher initial rate of copper dissolution, leaching process stopped. Addition of both ferrous and ferric iron to the bioleaching medium levelled off the copper extraction and had an inhibitory effect which decreased the final redox potential. The monitoring of ferrous iron, ferric iron and copper extraction in leach solutions gave helpful results to understand the behaviour of iron cations during chemical and bacterial leaching processes.

Non-ferrous Metal Industry in Hunan Province

In the last ten years (1982～1991) 2.26 Mt of 10 kinds of nonferrous metals had been pro-duced in Hunan Province. Up to date the mining capacity achieves 6.52 Mt, ore-dressing capacity--7.25 Mt, smelt capacity--334 kt and the processing capacity--113 kt. In 1991 the output of10 kinds of nonferrous metals amounted to 292.8 kt. At present Hunan Province produces alloys,oxides and other compounds for copper, aluminium, lead, zinc, antimony and mercury. Species ofrare-earth metals and its alloys produced in Hunan Province amount to 160 and more. In

National Plan for Non-ferrous Metals Production Fulfilled ahead of Time

Vice president of China National Nonferrous Metals Industries Corporation Mr. WoTingshu said:"The output of 10 kinds of nonferrous metals amounted to 2.45 Mt." This factmean1s that the national plan for nonferrous metals production fulfiled earlier. The 10 kinds ofnonferrous metals are aluminium, magnesium, lead, zinc, copper, tin, nickel, antimony mercuryand titanium.

Preliminary Announcement for International Symposium on Exploitation and Utilization of Titaniferrous Vanadio-magnetite

--An international symposium hostedby Panzhihua Iron and Steel Co.,co-orga-nized by The Chinese Society of Metalsand The Nonferrous Metals Society

Guangyuan Non-ferrous Metal Company

In the city Guangyuan,sited in the north of Sichuan Province,the Guangyuan Non-ferrousMetal Company had been established recently.The city plans to enter the non-ferrous metal indus-try in a list of key enterprises and to develop aluminium,lead and gold mainly.Some middle-scaleenterprices have been established,for example;Wuzhou Aluminium-electrolysis plant。

POLISHING OF NON-FERROUS METALS WITH HIGH EFFICIENCY

１ＩＮＴＲＯＤＵＣＴＩＯＮＢｅｓｉｄｅｓｓｔｅｅｌｓ，ｎｏｎｆｅｒｏｕｓｍｅｔａｌｓｓｕｃｈａｓａｌｕｍｉｎｉｕｍ，ｃｏｐｐｅｒ，ｔｉｔａｎｉｕｍａｎｄｔｈｅｉｒａｌｏｙｓａｒｅｖｅｒｙｉｍｐｏｒｔａｎｔｍａｔｅｒｉａｌｓ，ｄｕｅｔｏｔｈｅｉｒａ...

40th ANNIVERSARY COMMEMORATION MEETING OF NONFERROUS METELS JOURNAL HELD IN BEIJING

In March 12, former leaders in metallurgy industry circle Gao Yangwen, Lin Zesheng, Duan Dingbo, General Manager of China National Nonferrous Metals Industry Corporation(CNNC)Fei Ziwen, Vice General Manager He Boquan, Assistant General Manager Wu Gong, directors

Resolution of siderotic glaucoma correlated with decreased pigmentation in the anterior chamber angle after removal of a retained ferrous foreign body

Dear Sir,I am Dr.Zhe Xu,from the Eye Center,Second Affiliated Hospital,School of Medicine,Zhejiang University,Hangzhou,China.We write to present a case of resolution of siderotic glaucoma after removal of a retained ferrous foreign body.This study has been performed in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of the Second Affiliated Hospital.

Fe-MOF Derived Ferrous Hierarchically Porous Carbon Used as EF Cathode for PFOA Degradation

Pentadecafluorooctanoic acid (PFOA) is environmentally persistent, bioaccumulative, globally distributed and dangerous to human beings. Thus, the degradation of PFOA with effective method remains further exploration. Here, an Electro-Fenton (EF) system was studied for efficient PFOA degradation, and where a new composite material ferrous hierarchically porous carbon (FHPC) prepared by high temperature activation of MIL-100 (Fe) was applied as the cathode, and 81.4% PFOA (Initial 50 mg/L) elimination was achieved at a low potential of ?0.4 V (pH = 7, 3 h). With the increasing of the activated temperature, the catalytic ability of the materials is decreasing because the reduced surface area reduced and the iron nanoparticles size enlarged. Moreover, the H2O2 and the ?OH were also detected to confirm the dominating contribution of Electro-Fenton mechanism in the PFOA degradation. Thus, this material could be used in efficient heterogeneous EF technology for PFOA elimination.

Quality of Drugs Based on Ferrous Sulfate Dispensed in a Basic Health and Commercial Pharmacy in a City in the Amazon Region

Background: For the WHO, anemia is a serious public health problem, with an emphasis on deprivation anemia, which has socioeconomic conditions as determining factors for its development. Among nutritional anemias, the most relevant is iron deficiency, whose main form of prevention and treatment is supplementation with ferrous sulfate dispensed in the public health system, with the need to periodically check whether the drug has the quality required by regulatory health agencies. Thus, the objective of this study was to analyze the quality of the ferrous sulfate medication, from the same laboratory, and dispensed in a basic health unit (BHU) and a commercial pharmacy (CF). Materials and Methods: An analytical, qualitative and quantitative study of ferrous sulfate heptahydrate (25 mg/mL in 100 mL syrup), carried out on 20 BHU and 10 from CF, both from the same laboratory, but in different batches. Samples were subjected to organoleptic analysis and verification of iron content, pH, volume and density. Data were compared with values recommended by the Brazilian pharmacopoeia 5th edition. Results: Three batches were evaluated: 4659 of from the CF;4574 from the BHU1, and 4576 from the BHU2, stored in accordance with RDC 304/19 of ANVISA. All showed compliance with some organoleptic characteristics;and stable values in pH (3.61 - CF;3.67 - BHU1;3.65 - BHU2), density (1.079 - CF;1.088 - BHU1;1.086 - BHU2) and individual volume (not less than 95% of the declared value). However, it was not possible to detect the odor of herbs;the average volume of batch BHU1 was below the declared value, and the iron content of both BHUs was above the maximum value of pharmacopoeia standards. Conclusion: Samples did not show full compliance with the physical and chemical parameters evaluated, suggesting deviation in the quality of the medication.

Using Ferrous Ion for the Reductive Degradation of Hexavalent Chromium

This paper discusses the toxicity and mobility of chromium species. And it presents the extent and kinetics of reductive remediation of hexavalent chromium, Cr+ using ferrous ion, Fe2+. Molar ratios of 1:3 and 1:6 of Cr (VI) to Fe (II) were used. Integral method of data analysis showed reaction followed second-order kinetics with R square values near unity. Reaction was initially fast but with a rapid precipitation attributed to Cr (III)-Fe (III) in previous studies. This colloidal precipitate ultimately stops the reaction, which explains while conversion efficiency increases with increased molar ratio of Cr (VI) to Fe (II). The impact of pH was investigated by adjusting the Cr (VI)-Fe (II) medium to pH 2.78, 5.24, 7.00, 9.00 and 11.96 using predetermined drops of acid or base. Reaction was more rapid under alkaline conditions with higher extent of degradation consistent with previous research. In soil system, mass transfer limitation was hardly noticed as high extent of reduction was recorded relative to aqueous phase. The high solubility of Cr (VI) aided the release into the aqueous media for reduction by ferrous sulfate.

Reuse of Ferric Sludge by Ferrous Sulfide in the Fenton Process for Nonylphenol Ethoxylates Wastewater Treatment

In this paper, Fenton process was determined to be an effective technique to treat the refractory Nonylphenol ethoxylates (NPEOs) wastewater. The COD removal efficien-cies above 89% were obtained when the initial COD concentration was 12000mg/L. However, A large number of ferric sludge (SS=8.724g/L) would be produced after the Fenton oxidation of the wastewater and must be disposed appropriately. A novel process for Fenton sludge reused by low-cost ferrous sulfide (FeS) was also investi-gated. Experimental results show that the Fenton sludge could be reduced to produce a certain amount of Fe2+ in the acidic mixed liquor by ferrous sulfide. This mixed liquor from Fenton sludge could be used as the new catalyst in the Fenton process and was also highly effective for the NPEOs wastewater treatment. The residual ferrous sulfide from the mixed liquor could be used for the next batch of the

A Mild and Practical Procedure for Tetrahydropyranylation of Alcohols and Phenols Catalysed by Anhydrous Ferrous Sulfate

An easy preparation of tetrahydropyranyl (THP) ethers of alcohols andphenols with 3,4-dihydro-2H-pyran (DHP) in refluxing dichloromethane has been carriedout in good to excellent yields under catalysis of anhydrous ferrous sulfate.

Synergistic improvement of nitrogen and phosphorus removal in constructed wetlands by the addition of solid iron substrates and ferrous irons

Sanjiang Plain is intensively used for rice production,and ditch drainage diffuse pollution prevention is crucial.Groundwater,rich in Fe ions,is the main source of irrigation water in this region.In this study,pyrite and zero-valent iron(ZVI)(sponge iron and iron scraps)were used as substrates to identify the synergistic influence of exogenous Fe^(2+)addition and solid iron substrates on pollutant removal in constructed wetlands.Based on the results,iron substrates hardly improved the ammonia removal,mainly because of the physical structure and oxidation activity.At a hydraulic retention time longer than 8 h,the pollution removal efficiency in the zero-valent iron(ZVI)substrate treatment increased significantly,and the removal of nitrate(NO_(3)^(−)-N)and total phosphorus(TP)in the iron scrap substrate treatment reached about 60%and 70%,respectively.The high-throughput sequencing results showed a significant increase in the abundance of microorganisms involved in denitrification and phosphate accumulation in biofilms on ZVI substrates.The highest diversities of such microorganisms in biofilms on iron scraps were found for denitrifying bacteria(Pseudomonas),nitrate-reducing Fe(II)-oxidizing bacteria(Acidovorax),and Dechloromonas with autotrophic denitrification and phosphate accumulation,with a 43%cumulative abundance.Dechloromonas dominated in the iron sponge substrate treatment.The highest relative abundance of Acidovorax was found in the mixed iron substrate(pyrite,sponge iron,and iron scraps)treatment.The addition of ZVI substrate significantly improved the removal of NO^(3)_(−)-N and TP and reduced the hydraulic retention time through the continuous release of Fe^(2+)and the promotion of microbial growth.When designing constructed wetlands for treating paddy field drainage,the appropriate addition of iron scrap substrates is recommended to enhance the pollutant removal efficiency and shock load resistance of CWs.