Negative effect of dissolved organic compounds on settling behavior of synthetic monominerals in red mud

Hydration grossular and hematite monominerals were synthesized. The effects of dissolved organic compounds(including sodium formate, sodium acetate, sodium oxalate, sodium salicylate or disodium phthalate) on the settling performance of hydration grossular or hematite slurries were studied. The settling of the slurries was also investigated with the addition of sodium polyacrylate(PAAS) or hydroxamated polyacrylamide flocculant(HCPAM). The adsorption mechanism of organic compounds on monominerals surfaces was studied by FT-IR and XPS, respectively. A deterioration in settling is observed in order of disodium phthalatesodium salicylatesodium oxalatesodium formate(or sodium acetate). Moreover, PAAS can efficiently eliminate the negative effects of organic compounds on the settling performance of the hydration grossular slurry. HCPAM can efficiently eliminate the negative effects of sodium formate, sodium acetate and sodium oxalate on the settling performance of the hematite slurry, but it only partially improves the settling performance of hematite slurry containing sodium salicylate or disodium phthalate. FT-IR and XPS results show that organic compounds are physically adsorbed on hydration grossular surface, and chemisorptions of organic compounds occur on hematite surface with a bidentate chelating complex.     

FTIR analysis of adsorption of poly diallyl-dimethyl-ammonium chloride on kaolinite

The flocculation behavior of ultrafine kaolinite suspension was investigated through settlement tests and FTIR method was employed to probe the adsorption mechanism of flocculant on kaolinite. The results show that the maximum settling rate of kaolinite occurs at pH value of 3.33,which is close to the point of zero charge（PZC） of kaolinite （3.5）. This result is in good agreement with the double electric layer theory. Kaolinite suspension reaches the largest settling rate at a low concentration of 39 g/t for poly diallyl-dimethyl-ammonium chloride（PDADMA） flocculant,whereas for polyacrylamides（PAM） the dosage is required to be 500 g/t. When macromolecule polymer is adsorbed on surface,kaolinite particles may be flocculant due to the bridging effect. There are cation flocculant characteristic bands on the spectrum of kaolinite but no obvious shifting. Thus,the adsorption of poly diallyl-dimethyl-ammonium chloride on kaolinite surface is physical adsorption.     

正交法在高泥化煤泥水沉降试验中的应用

为了减少药剂用量,采用单因素试验优选法初步确定煤泥水沉降絮凝剂和无机凝聚剂合理的用量范围,在此基础上确定絮凝剂和无机凝聚剂两个因素的具体水平;以煤泥水初始沉降速度和上清液透光率为考察指标,利用正交试验方法对絮凝剂和无机凝聚剂用量配比进行了优化。结果表明,分子量为1 200万的聚丙烯酰胺（PAM）用量为6.8 g/m3,CaCl2用量为350g/m3时,可以取得很好效果,上清液透光率可达97.70%,初始沉降速度达22.32 cm/min。     

地下水中砷去除机理实验研究

为了研究地下水中砷的去除机理,采用吸附和土柱模拟实验,研究了不同吸附介质、初始浓度和价态等因素对砷去除的影响.吸附实验结果表明,As(Ⅴ)在初始浓度为0.05 mmol/L的条件下,在水铁矿和针铁矿上的平均吸附率分别为35%和14%;As(Ⅴ)在初始浓度为0.01 mmol/L条件下,在水铁矿和针铁矿上的平均吸附率分别为87%和37%;As(Ⅲ)在初始浓度为0.01 mmol/L的条件下,在水铁矿和针铁矿上的平均吸附率分别为73%和39%.土柱模拟实验结果表明,As(Ⅴ)在细砂中的平均吸附率为72%,而在加入氢氧化铁的细砂中平均吸附率为93%;As(Ⅴ)在粗砂中的平均吸附率为80%,在加入氢氧化铁的粗砂中平均吸附率为93%;As(Ⅲ)在细砂和粗砂中的平均吸附率为99.9%.结果表明,砂土中加入Fe3+和OH-后由于产生的氢氧化铁有利于As的吸附,粗砂和细砂对As(Ⅲ)的吸附较强.     

Settling characteristics of ultrafine iron ore slimes

The slurry settling characteristcs are the most important to design a thickener in process industries.In this work,the iron ore slurry from the screw classifier overflow was used for the settling study...     

铁锰氧化物对苯酚氧化降解的实验研究

为了考察铁锰氧化物对酚类污染物的氧化降解能力,采用天然以及合成的铁锰氧化物对苯酚的氧化降解进行对比实验研究。土壤中铁锰氧化物样品分别为天然针铁矿及氧化锰,合成铁锰氧化物样品分别为合成针铁矿及软锰矿。结果表明:苯酚与铁锰氧化物发生氧化还原作用时,还可能与土壤中杂质发生吸附等作用;铁锰氧化物还原反应强度随着反应介质pH值的升高而迅速下降;可用零级反应动力学方程拟合铁氧化物还原溶解反应,针铁矿溶解反应的强度与介质的pH值呈负相关关系;天然针铁矿对酚类污染物的氧化降解能力明显高于合成针铁矿,pH值对天然针铁矿溶解反应影响较大;可用一级指数衰减方程拟合锰氧化物还原溶解反应,锰氧化物溶解反应的强度与介质的pH值呈指数衰减关系;pH值对软锰矿还原溶解反应的影响大于对土壤中氧化锰的影响,pH值越小,影响越显著;对比pH值对铁和锰还原作用的影响发现,在pH=6.5时,锰氧化物仍有较强的氧化性能。     

SYNERGISTIC EFFECT OF MINERAL SURFACE CONSTITUENTS IN DEXTRIN ADSORPTION

Abstract:As part of a systematic research on the interaction mechanismbetween polysaccharides and mineral surfaces,we extend the studies ondextrin adsorption to real minerals such as oxides and salt-type minerals,based on previous studies of model systems(surface-modified quartz).Theminerals tested include hematite,rutile,fluorite,calcite,apatite,etc.Itis obseroed that dextrin adsorption on these minerals is strongly pH-depen-dent,with adsorption maxima appearing at pH values around the isoelec-tric points of the minerals,indicating interactions with surface metal hydroxide species.X-ray photoelectron spectroscopy(XPS)measurements re-veal electronic binding energy shifts or Auger parameter changes Of miner-al surface elements after dextrin adsorption,pointing to a chemical mecha-nism of interaction.Furthermore,it is observed that the reaction of miner-als with moderate amounts of fatty acids prior to dextrin addition resultsin an increase in dextrin adsorption,whereas excessive fatty acids do theOpposite     

Novel polyhydroxy cationic collector N-(2,3-propanediol)-N-dodecylamine: Synthesis and flotation performance to hematite and quartz

To enhance the performance of traditional cationic collector, a novel polyhydroxy amine collector N-(2,3-Propanediol)-N-dodecylamine(PDDA) was designed by introducing one propylene glycol group into dodecylamine(DDA). It was prepared by a nucleophilic substitution reaction, which showed better solubility and hydrophobicity than DDA and was firstly employed as the collector for the separation of hematite and quartz. Flotation tests showed that PDDA had an excellent flotation performance and signi...     

Adsorption mechanism of N-laurel-1,3-diaminopropane in a hematite-quartz flotation system

The strong collecting performance of N-laurel-13-diaminopropane (ND13) with respect to quartz encouraged us to study its separation of hematite and quartz mixtures in a laboratory cell flotation test.The results show that the best separation results can be achieved when the pulp pH is 7.27 and 583 mg/L collector plus 6.67 mg/L depressant are added to the mixture. Products with 58.45%, 62.78% and 63.72%iron grades can be achieved respectively when mass ratio of hematite to quartz is 2:3, 1:1, and 3:2. The adsorption mechanism of ND13 on a quartz surface was investigated by zeta-potential and X-ray photoelectron spectroscopy measurements. The results reveal that electrostatic and hydrogen bonding adsorption take place between ND13 and the quartz surface, and that ND13 mainly interacts with the oxygen atoms on the quartz surface.     

Effect of bastnaesite as reductant on hematite reduction during in-situ suspension magnetization roasting of refractory iron ore under neutral atmosphere

The iron tailings of Bayan Obo mines are solid waste, which occupies land area and also causes environmental pollution; however, this waste can be recycled. In this study, based on the characteristics of iron minerals and fluorocarbonate contained in Bayan Obo iron tailings, clean magnetization roasting of iron minerals by bastnaesite from iron tailings during in-situ suspension magnetization roasting in a neutral atmosphere was explored. The results show that for iron tailings with a mass of 12 g, a N₂ gas flow rate of 600 mL/min, and roasting for 5 min at 800 °C, iron concentrate with a 60.44% iron grade at an iron recovery of 76.04% could be obtained. X-ray diffraction analysis showed that the weak magnetic hematite was reduced to strong magnetic magnetite in the neutral atmosphere, without additional reductant. The kinetics of the magnetization roasting of mineral mixtures (bastnaesite and hematite) in a neutral atmosphere showed that the optimal reaction mechanism function was the three-dimensional diffusion model with activation energy of 161.8838 kJ·mol^?1; this indicates that the reaction was a heterogeneous, diffusion-controlled solid-state reaction.     

Effect and mechanism of dolomite with different size fractions on hematite flotation using sodium oleate as collector

The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at p H of about 9. The effect mechanism of dolomite on hematite flotation was investigated by means of solution chemistry, ultraviolet spectrophotometry(UV), inductively coupled plasma atomic emission spectrometry(ICP-AES) and X-ray photoelectron spectroscopy(XPS). It is observed that dolomite with different size fractions has depressing effect on hematite flotation using sodium oleate as collector, and dolomite could be the "mineral depressant" of hematite using sodium oleate as collector. The reasons for that are concerned with sodium oleate consumption and the adsorption onto hematite of dissolved species of dolomite.     

Adsorption of sodium oleate at the microfine hematite/aqueous solution interface and its consequences for flotation

The adsorption of sodium oleate(NaOL) at the microfine hematite/aqueous solution interface was investigated in this paper. Experimental research indicated that negative effects stemmed from the dissolution of the microfine hematite(D50=19.21 μm) could be effectively eliminated via the appropriate dosage of NaOL at alkali pH conditions. Solution chemistry calculation and adsorption test results indicated that RCOO^- and(RCOO)₂^2- ions were responsible for microfine ...     

负载型Al(OH)3/SiO2的合成及对铀酰的吸附性能

制备了负载型吸附剂Al(OH)₃/SiO₂,研究其对铀酰离子的吸附行为。分别考察了吸附剂质量、溶液pH、初始浓度、温度和吸附时间对吸附性能的影响;结合吸附等温线、热力学以及动力学初步研究了吸附机理,并探究了共存离子和富里酸对吸附性能的影响。结果表明,当吸附剂质量0.03 g、pH=5、初始浓度1 mmol/L、温度303 K、吸附时间60 min时,最大吸附量为110.4 mg/g,可以重复使用4次;Al(OH)₃/SiO2对铀酰离子的吸附过程是吸热且自发进行,以单分子层吸附为主,吸附行为符合准二级动力学模型,化学吸附是速率控制步骤。     

混凝法处理胜利油田聚合物驱采出水效果研究

采用化学混凝法处理胜利油田聚合物驱采出水,并在比较不同单一混凝剂的除油、除浊效果基础上,进行了混凝剂的优化复配。结果表明:传统铝盐和传统铁盐混凝剂的除油、除浊效果明显优于无机高分子混凝剂和有机高分子絮凝剂。氯化铁和氯化铝按投加量质量比为1:3比例复配时,不但能提高絮体的沉降速度,减少污泥量,而且能达到较高的除油、除浊效果。复配铁铝混凝剂与阴离子聚丙烯酰胺(APAM)三元复配时,除油、除浊效果主要决定于无机复配铁铝混凝剂的投加量;投加0.5mg/L的APAM便能使絮体进一步发生桥联作用,提高沉降性和减少污泥体积。     

蛋白絮凝剂去除水中新兴污染物研究进展

蛋白絮凝剂是一类由动植物或微生物产生的,可使液体中不易降解的固体悬浮颗粒聚集和沉淀的特殊高分子物质。蛋白絮凝剂因具有良好的吸附性能和絮凝性可被直接作为某些地区的净水剂。近年来,随着天然水处理剂的蓬勃发展,蛋白絮凝剂作为高效、绿色、环保的絮凝剂广受科研人员的青睐。总结蛋白絮凝剂的提取纯化方法、分子结构和有效官能团等特性,概括蛋白絮凝剂用于去除水中新兴污染物的研究现状、性能和机理,并对蛋白絮凝剂去除水环境中的新兴污染物进行展望。蛋白絮凝剂作为水处理药剂具有一定优势,未来可通过对蛋白絮凝剂进行深入研究,发掘其在去除水中新兴污染物的潜在价值,为提高水环境安全提供一种新途径。     

Evaluation of flocculation characteristics of kaolinite dispersion system using guar gum: A green flocculant

This paper reports the systematic investigation on the flocculation, sedimentation and consolidation characteristics of kaolinite using guar gum as a green flocculant. In-situ flocculation behavior of kaolinite at various pH, guar gum dosages, and ionic strength were studied using a light scattering technique. The effect of these parameters on the settling rate, solid consolidation, and supernatant liquid clarity was recorded. The morphology of kaolinite and flocculated kaolinite aggregates were analyzed using FESEM. The morphology studies suggest that it is poorly crystalline with multiple steps on edge, broken edge; laminar with high aspect ratio and have rough basal surface. The complex irregularity on the basal surface and the presence of multiple steps in the edges, broken edges(hydroxyl groups) have facilitated the guar gum adsorption. The isoelectric point of kaolinite is pH 3.96. The p H, ionic strength and flocculant dosage have a significant effect on the kaolinite settling rate. The guar gum has exhibited excellent turbidity removal efficiency at pH 5. The turbidity removal is inefficient at pH 10. However, guar gum has shown high turbidity removal with 80% transmission at pH 10 in the presence of a KNO_3 electrolyte.     

SBAR中好氧颗粒污泥的培养与应用研究

以普通絮状活性污泥为接种污泥,采用人工配制的模拟生活污水,通过逐步缩短沉降时间的方法,在SBAR中成功地培养出了成熟的好氧颗粒污泥。颗粒污泥的SVI为19．97mL／g,粒径在0．45～2．0mm之间,平均沉降速率为45．62m／h,SOUR为47．68g／kg·h,均优于普通絮状污泥。通过扫描电镜观察,颗粒污泥表面粗糙,轮廓清晰,分布着一些沟壑和微小孔道,微生物以杆菌和球菌为主。研究表明,该好氧颗粒污泥反应器具有良好的去除COD和NH4^＋-N的能力,去除率分别达到93％和98％以上,对TP的去除率也达到了60％左右。     

超细CaCO_3合成中碳化机理的研究

利用电导仪跟踪碳化反应历程,结果显示在高的Ｃａ（ＯＨ）２浓度下,ＣＯ２的传质过程是整个碳化反应的控制步骤;在低的Ｃａ（ＯＨ）２浓度下,Ｃａ（ＯＨ）２的溶解过程是碳化反应的控制步骤。     

羟基丁二酸对α－Fe_2O_3单分散溶胶的絮凝──稳定性

研究了羟基酸系列之一的羟基丁二酸（苹果酸）体系对α－Ｆｅ＿２Ｏ＿３单分散溶胶稳定性的影响，讨论了该体系的絮凝机理．实验表明：①羟基丁二酸对α－Ｆｅ＿２Ｏ＿３溶胶的聚沿作用有别于一般电解质．②影响该体系的絮－稳定性的主要因素是体系的酸度和絮凝剂浓度．③羟基丁二酸对α－Ｆｅ＿２Ｏ＿３单分散溶胶的絮凝和再稳定是受表面化学反应所控制．属于特殊吸附絮凝．     

Fourier Transform Infrared Spectroscopic Studies in Flotation

Fourier transform infrared (FTIR) spectroscopy has been extensively employed In flotation research. The work done by the author and co-workers has been reported. A comparison has been made among the different FTIR specfroscopic techniques, e.g. , transmission FTIR spectroscopy, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and attenuated total reflectance (ATR) FTIR spectroscopy. FTIR spectroscopy has been used to study the mechanism of interaction between the collector and the surfaces of different minerals, the mechanism of action of the depressant in improving the selectivity of flotation, and the mechanism of adsorption of the polymeric modifying reagent on mineral surfaces. The interaction between particles in mineral suspension has also been studied by FTIR spectroscopy.