利用乙醇水溶液从含铁硫酸铝中除铁

  摘 要：为了从硫酸铝中除铁,提出了利用乙醇水溶液对含铁硫酸铝进行除铁的工艺方法。研究了乙醇水溶液的pH、温度、振荡时间对除铁率的影响以及乙醇回收并循环使用的工艺方法。通过实验确定了最佳的工艺参数：乙醇水溶液的pH≤1,温度为25 ℃,振荡时间为2.5 h。经4级逆流除铁,硫酸铝的含铁质量分数可由0.98%降至0.005%以下。负载在乙醇水溶液中的铁经双氧水氧化、氨水沉淀、过滤并蒸馏至干后,乙醇回收率可达99.5%以上。本工艺具有操作简单、无污染、成本低等优点。     

Influence of particle surface properties on film formation from precipitated calcium carbonate/latex blends

The surface properties of films prepared from a blend of precipitated calcium carbonate pigment (PCC) and poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) [P(BMA/BA); T_g = 0°C] latex were investigated in terms of the surface characteristics of the PCC and P(BMA/BA) latex particles. It was found that the presence of carboxyl groups on the P(BMA/BA) latex particles significantly improved the uniformity of the distribution of the PCC particles within the P(BMA/BA) copolymer matrix and the gloss of the resulting films. This phenomenon could be explained by an acid‐base reaction between the PCC particles and the carboxylated P(BMA/BA) latex particles. Studies on the influence of the composition of PCC/P(BMA/BA) latex blends on the gloss and transparency of the films were also performed, which led to the determination of the critical pigment volume concentration (CPVC) of this system, which was found to be 42 vol %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 891–900, 2002     

煤矸石低温中和过程铁、钙、镁的溶出及动力学

立足于贵州盘州丰富的煤矸石资源,为探求其高值化开发利用途径,采用硫酸浸取法对煤矸石中铁、钙、镁的提取过程进行研究。研究结果表明：在中和反应过程中,随着温度的升高,铁、钙、镁的溶出逐渐增加,最后趋于平稳,温度对铁、镁溶出率的影响较为显著,对钙溶出的影响相对较小。因此,选择低温中和过程作为铁、钙、镁溶出动力学研究。动力学研究结果表明：煤矸石中和过程中铁、钙、镁溶出的活化能分别为19.523kJ/mol、8.300 kJ/mol和27.565 kJ/mol,E_a钙＜E_a铁＜E_a镁,说明在煤矸石硫酸浸出中和反应过程中钙的溶出最容易,铁次之,镁的溶出相对较难;浸出过程的动力学控制类型属于内扩散控制,可用动力学方程\mathrm{1}\text{-}\frac{\mathrm{2}}{\mathrm{3}}x\text{-}{\left(\mathrm{1}\text{-}x\right)}^{\frac{\mathrm{2}}{\mathrm{3}}}\text{=}kt来描述。通过对固相物质XRD、SEM的表征,初步对煤矸石中的碳酸盐酸浸溶出过程进行了机理分析,为工业生产中煤矸石的高效利用提供了技术指导和理论支撑。     

碳酸钙渣悬浮态煅烧工业试验线工艺控制研究

碳酸钙渣是磷石膏生产硫酸铵时排放的废渣,其成分受制于硫酸铵生产线,主要矿物成分为碳酸钙,碳酸钙干基含量为72%～78%（质量分数,下同）,水分含量为15%～28%,且二者含量波动较大。贵州瓮福磷肥厂采用高固气比悬浮煅烧-快速冷却技术建成一条碳酸钙渣制备活性石灰的工业试验线,将石灰产品用于处理污水和生产建材。根据工业试验线的工艺调试经验,初步总结出该生产线的工艺控制要点和主要工艺参数的控制范围,并对生产线的优化改进提出建议,作为生产实践的参考。     

Synthesis of ethylene carbonate from urea and ethylene glycol over zinc/iron oxide catalyst

BACKGROUND: Ethylene carbonate (EC) was synthesised via urea and ethylene glycol (EG) over zinc/iron oxide catalyst. By so doing, the by‐product, EG, generated in the process of producing dimethyl carbonate by the transesterification route was converted back to the raw material, EC. The reaction mechanism of EC synthesis was also investigated by means of gas chromatography/mass spectrometry and in situ Fourier transform infrared/attenuated total reflection spectroscopy. RESULTS: Suitable conditions for the preparation of zinc/iron oxide catalyst were as follows: zinc acetate and iron nitrate as precursors, Zn/Fe molar ratio 8:1, calcination temperature 350 °C and calcination time 4 h. Characterisation by X‐ray diffraction revealed two different crystal phases: ZnO and ZnFe₂O₄. The highest yield of EC (66.1%) was obtained under the following conditions: reaction temperature 150 °C, reaction time 2.5 h, catalyst weight percentage 1.5% and urea/EG molar ratio 1:8. The study of the reaction mechanism revealed that the reaction for the synthesis of EC proceeded in two steps. CONCLUSION: The synergistic effect of ZnO and ZnFe₂O₄ promoted the catalytic performance of zinc/iron oxide. Copyright © 2008 Society of Chemical Industry     

Thermal decomposition of pure and rhodium impregnated cerium(III) carbonate hydrate in different atmospheres

The thermal decomposition of pure and rhodium impregnated cerium(III) carbonate hydrate in oxidising, reducing and inert atmospheres has been studied using combined thermogravimetry/mass spectrometry (TG/MS) and X-ray photoelectron spectroscopy (XPS). In oxygen, the decomposition of the pure carbonate proceeds in two steps, yielding H₂O,CO₂, and cerium(IV) oxide. In inert or reducing atmospheres, the second decomposition step is shifted towards higher temperatures and is divided into two parts. In the second part, CO₂ evolved is partly reduced by Ce(III) to CO and to elemental carbon, and non-stoichiometric CeO_2–x is formed as the solid product. In the presence of rhodium as a reduction catalyst, decomposition in helium yields hydrogen and less carbon monoxide than that of the pure carbonate, due to the water-gas shift activity of the solid. In hydrogen, quantitative reduction of the carbon dioxide evolved to methane and water is observed when rhodium is present.     

利用低浓度CO_2矿化磷石膏制硫酸铵和碳酸钙技术

针对目前CO_2减排和磷石膏处理的问题,中石化与四川大学合作开展了利用低浓度CO_2矿化磷石膏联产硫基复肥与碳酸钙的技术研究,并逐步推进该技术产业化。该项目以废治废,把捕集与利用两个环节合二为一,节省成本,具有显著的环境效益和社会效益。     

Response of subterranean clover (Trifolium subterraneum) to lime,magnesium, and boron on acid infertile soil in subtropical China

Severe symptoms observed in clover pastures sown in north Guangdong Province, China, warranted study of the response to Mg fertilizer, and possible interactions with lime and B fertilizer. Subterranean clover (Trifolium subterraneum) was sown in a 2 × 2 × 2 factorial pot experiment with Mg, lime, and B treatments and four replications. The highly acid soil collected from Lechang Model Cattle Farm was low in exchangeable Mg (0.06 meq 100 g^–1). Mg fertilizer doubled exchangeable Mg, increased Mg saturation to > 3% and raised the Mg/K ratio to > 1.0, but A1 saturation remained above 75%. Lime application doubled exchangeable Ca and reduced A1 saturation to < 1%, but did not affect exchangeable Mg or K levels.Clover yield increased (P < 0.01) with Mg application at 100 kg Mg ha^–1, but was not affected by lime or B fertilizer. Regression analyses showed that exchangeable Mg, soil Mg/K ratio, and Mg concentration in tops each accounted for > 70% of yield variation. Yield decreased markedly when exchangeable Mg was < 0.22 meq, soil Mg/K ratio was < 1.0, and when Mg in top growth fell below 0.15%. Symptom scores for Mg deficiency (including reddening and necrosis on older leaves) were correlated with yield (R² = 0.88) and tissue Mg (R² = 0.92). Plants without symptoms were present only where tissue Mg was > 0.26%. Liming to amend soil acidity did not increase tissue Mg or correct deficiency symptoms in clover plants without added Mg, but did reduce P and B to below critical levels. B deficiency did not limit pasture growth and application of 4 kg B ha^–1 was sufficient to raise B level in clover tops to > 25 mg kg^–1 on lime amended soil.The implications of correction of this acute Mg deficiency in relation to future fertilizer programs (especially K fertilizer) for crops and pastures grown on China's weathered red soils is discussed, as are the problems associated with grazing livestock on Mg deficient pastures.     

Removal behavior of Cu(II) during Cr(VI) reduction by cast iron powder in absence and presence of ultrasound

ABSTRACT

Cu(II) is an important and typical heavy metal ion in the wastewater containing Cr(VI), and its removal during Cr(VI) reduction by zero valent iron (ZVI) may make it separately be recovered as a kind of copper resource. In this study, the removal behavior of Cu(II) during Cr(VI) reduction by cast iron powder in absence and presence of ultrasound was investigated by atomic absorption spectrometry (AAS), X-ray powder diffractometer (XRD), scanning electron microscope-energy dispersion spectrum (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The AAS tests indicated that the ultrasound could not only obviously enhance the removal of Cu(II) but also improve the reduction rate of Cr(VI). The XRD and SEM-EDS analyses showed that Cu(II) in the solution was reduced to metallic copper and then was deposited at the surface of ZVI. The ultrasound could remove the Fe-Cr oxides and hydroxides at the ZVI surfaces, resulting in the active surfaces of iron increased. The XPS analyses demonstrated that the surface of metallic copper would be transformed into the film of copper oxide (CuO) in the ultrasound system. The obtained metallic copper and copper oxide could be recovered alone by traditional method of the acid pickling.     

Leaching loss of calcium,magnesium, potassium and nitrate derived from soil,lime and fertilizers as influenced by urea applied to undisturbed lysimeters in south-east Nigeria

Calcium hydroxide was applied to monolith lysimeters at Onne in south-east Nigeria. Eight lysimeters were cropped with maize followed by upland rice and four were uncropped. The cropped and two uncropped lysimeters received Mg, K and urea in the first season. Two uncropped lysimeters received no fertilizers. Drainage water was collected during the two growing seasons and analyzed for calcium, magnesium, potassium, sodium, nitrate and chloride. The fertilizer applied in the second season was not leached during the year of application.The cropped lysimeters lost 27 percent of the sum of the exchangeable Ca in the soil profile and the calcium added, and 29 percent of the corresponding sum for Mg. With no crop, the losses increased to 34 and 37 percent, respectively, but with no crop or fertilizer, the losses were similar to those from the cropped lysimeters. The loss of potassium ranged from 6 percent from the unfertilized lysimeters to 10 percent in the cropped lysimeters. The amounts of sodium leached ranged from 29 to 35 kg Na ha^–1. The bulk of the calcium and magnesium leached from calcium hydroxide and fertilizers occurred in the second season when the loss was in good agreement with the amount of nitrate lost giving (Ca + Mg)/NO₃ charge ratios of approximately one. Urea increased the amount of nitrate leached and led to a corresponding increase in the amounts of calcium and magnesium lost in the drainage water. The charge ratio remained unchanged when the cations were leached only with nitrate derived from the mineralization of soil organic matter. In the cropped lysimeters, this source accounted for about four times more nitrate in the drainage water than the fertilizer.     

中国钢铁行业“超低排放”向“减污降碳”过渡的技术思考

钢铁行业是我国国民经济的重要基础产业,但同时也是我国污-碳排放量最大的工业行业。2019年4月,五部委联合印发了《关于推进实施钢铁行业超低排放的意见》,率先引领了工业烟气超低排放,我国钢铁行业大气污染排放量实现了大幅削减。“十四五”以来,在“双碳”背景下,随着减污降碳的提出,现有超低排放技术所带来的碳增量效应问题逐渐凸显,又对钢铁行业带来了新的技术需求。本工作阐述了我国钢铁行业超低排放的技术进展,归纳了钢铁行业减污降碳发展方向,并提出了未来钢铁行业绿色低碳发展建议,为推动中国钢铁行业的高质量绿色发展提供参考。     

Film formation from pigmented latex systems: Drying kinetics and bulk morphologies of ground calcium carbonate/functionalized poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) blend films

The drying kinetics and bulk morphology of pigmented latex films obtained from poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) latex particles functionalized with carboxyl groups and ground calcium carbonate blends were studied. Latex/pigment blends with higher carboxyl group coverage on the latex particle surfaces dried faster than films with few or no carboxyl groups present. The latex/pigment dispersions also dried faster when there was more stabilizer present in the blend system because of the hydrophilic nature of the stabilizer. The net effect of increasing the pigment volume concentration in the blend system was to shorten the drying time. The bulk morphologies of the freeze‐fractured surfaces of the pigmented latex films were studied with scanning electron microscopy. Scanning electron microscopy analysis showed that increased surface coverage of carboxyl groups on the latex particles in the latex/pigment blends resulted in the formation of smaller pigment aggregates with a more uniform size distribution in the blend films. In addition, the use of smaller latex particles in the blends reduced the ground calcium carbonate pigment aggregate size in the resulting films. Scanning electron microscopy analysis also showed that when the initial stabilizer coverage on the latex particles was equal to 18%, smaller aggregates of ground calcium carbonate were distributed within the copolymer matrix of the blend films in comparison with the cases for which the initial stabilizer coverage on the latex particles was 8 or 36%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2267–2277, 2006