PURIFICATION OF KAOLINS BY SELECTIVE DISPERSION AND FLOCCULATION

To fulfill the increasingly higher requirements on thequality of kaolins from industries, the purification of kaolins has becomemore and more important. Kaolins from different mines were studied withthe aim to remove the various impurities. The mineralogical studies on thekaolins indicated that kaolinite and the major gangue minerals in the orewere all very fine. Therefore, it was difficult to separate kaolinite fromthe gangue minerals by conventional mineral processing techniques,such asgravity concentration, magnetic separation and flotation. Techniques forfine particles processing, i. e. selective dispersion and flocculation weretried to purify the kaolins. The experiments were first carried out withpure minerals of kaolinite and the gangue,minerals to study the dispersionand flocculation characteristics of the different mineral suspensions undervarious conditions. The key factors affecting the dispersion and floccula-tion of the minerals in water were the pH of the suspension, the type anddosage of t     

Selective flocculation of iron oxide-kaolin mixtures using a modified polyacrylamide flocculant

High molecular weight polyacrylamides were synthesized and successfully modified to contain up to 8·3% hydroxamate functional groups. The selective flocculation tests carried out on 1:1 iron oxide/kaolin mixtures using parent polyacrylamide, polyacrylic acid and the modified polyacrylamide, confirm the possibility of enhancing selectivity through introduction of iron chelating functional groups in commercially available polymers. Starting with a feed grade of 35% iron, 92% recovery with acceptable grade of 60% iron has been achieved using the modified polyacrylamide. NCL communication No. 4415     

Behavior of Fe, Mn, Cu and Cd in the duwamish river estuary downstream of a sewage treatment plant

The behavior of dissolved Fe, Mn, Cu and Cd in the Duwamish River downstream of a sewage treatment plant located near Seattle, Washington, was investigated in three distinct zones: (1) immediately downstream of the effluent outfall, (2) further downstream in the freshwater portion of the river and (3) in the estuarine mixing zone. A three-end-member tracer model utilizing salinity and dissolved inorganic nitrogen was developed to distinguish physical mixing processes from biogeochemical reactions. The results of this investigation indicate that Fe was removed from the dissolved phase onto particulates near the plant. Although no additional reactions controlled the distribution of dissolved Fe, Mn and Cu in the freshwater portion of the river, Cd was removed from the dissolved phase. In the estuarine mixing zone, a significant fraction of the dissolved Fe and Cu was removed from solution, while Mn and Cd desorbed from particulates. The chemical forms of the trace metals rather than their sources appear to determine their participation in these reactions.     

ULTRASOUND IN THE SUSPENSION SEPARATION METHODS

Investigations were carried out on the effect of the ultrasonic field and some selected chemical compounds on the process of preparing sludges to be dewatered by mechanical devices.

The tests; were performed in a laboratory on real sludges. The processes occurring in sludges due to presence of ultrasonic field and applied chemical reagents were determined on the basis of a commonly used method of determining the sludge dewatering, in both filtration and sedimentation.

The interdependences of value changes of the above mentioned factors and the possibilities of applying ultrasonic waves to intensifying sludge dewatering process were examined. The obtained results confirm the applicability of ultrasonic waves to the process of sludge treatment and prove that the initial assumptions concerning the use of ultrasonic field in the suspension separation methods to be valid.     

Sequence of the open reading frame of the FL01 gene from Saccharomyces cerevisiae

The cloned part of the flocculation gene FLO1 of Saccharomyces cerevisiae (Teunissen, A.W.R.H., van den Berg, J.A. and Steensma, H.Y. (1993). Physical localization of the flocculation gene FLO1 on chromosome I of Saccharomyces cerevisiae, Yeast, in press) has been sequenced. The sequence contains a large open reading frame of 2685 bp. The amino acid sequence of the putative protein reveals a serine- and threonine-rich C-terminus (46%), the presence of repeated sequences and a possible secretion signal at the N-terminus. Although the sequence is not complete (we assume the missing fragment consists of repeat units), these data strongly suggest that the protein is located in the cell wall, and thus may be directly involved in the flocculation process.     

Submicron capsules extracted from rapeseed as novel flocculant agents for the treatment of turbid water

Flocculation is an important step in water treatment as it is responsible for the separation of suspended solids and colloids. The currently used flocculants have certain limitations with respect to environmental impact and disposal as well as potentially being harmful to human health, which has encouraged the study of natural flocculants originating from oleaginous plants. Oil-bodies are individual small organelles in which oleaginous seeds store triacylglycerols reserves. In this article, the flocculant properties of oil-bodies have been investigated. Oil-bodies flocculate at pH 5, 7 and 9 and high ionic strength (100 mM NaCl) and it was demonstrated that their intact structure is necessary for the flocculation activity as treatment with protease K and diethyl ether, that remove the protein coat and the oil-core, respectively, dramatically decreased the flocculation activity. This study shows that oil-bodies have the potential to be novel, natural, sustainable, environmentally friendly and biodegradable flocculant candidates for water treatment.     

新型栅条反应池在水处理中的应用

论述了一种新型的不锈钢栅条反应池在水处理中的应用效果。通过与传统的木网格反应池的生产性的对比试验，证明原水浊度较高时，该池反应的效果明显较好；但原水浊度较低时，没有明显优势。     

腈纶废丝改性水解物的制备及其絮凝效果

常压时在碱性条件下水解腈纶废丝可生成丙烯酰胺和丙烯酸的无规共聚物,此法在得到有机高分子絮凝剂的同时又能避免废腈纶对环境的污染。在常压、95～100℃下用乙二胺对废腈纶碱性水解物进行改性,制得含有酰胺基、羧钠基、羧基及羧铵基等活性基团的高分子絮凝剂,研究了改性水解产物对废水的絮凝性能,并由红外光谱对其结构进行了分析。结果表明,乙二胺在腈纶碱性水解过程中能够促进腈基的水解,改性水解物对废水的脱色、除浊、去油、除酚效果均明显优于水解产物,经测定其除浊、去油、除酚效果分别达到98%、70%、70%。     

搅拌槽内絮凝动力学研究

采用激光粒度仪在线测定并研究了搅拌槽内聚丙烯酰胺与磷矿酸解渣的絮凝动力学。考察了不同浓度的酸解液，絮凝剂加入量，温度，酸解渣原始平均粒径和搅拌强度对絮凝动力学影响。在实验研究范围，絮凝初始速度随温度升高，絮凝剂加入量及搅拌强度的增加而提高，但随着酸解液的粘度增加和酸解渣原始平均粒径的增大而降低，体系中存在最佳的絮凝剂加入量。通过酸解渣的电泳试验，用自合成的阴离子，阳离子改性絮凝剂以及非离子型絮凝剂与酸解渣的絮凝试验发现，在中性的水中，酸解渣与不同荷电类型的絮凝剂的絮凝速度大小依次为：阳离子型＞非离子型＞阴离子型。而在磷酸酸解料浆中絮凝速度与絮凝剂的荷电类型无关。磷矿酸解渣与聚丙酰胺絮凝剂的作用主要表现为架桥机理。     

聚丙烯酰胺在矿物加工领域的应用现状及策略

聚丙烯酰胺（PAM）作为矿物加工领域的一种外加剂,在不同工艺环节中具备不同的用途。本文分别介绍了PAM作为浓缩絮凝剂、选择性絮凝剂、过滤助滤剂以及其他用途药剂在矿物加工领域的应用研究现状。研究发现不同类型的PAM具有不同用途特点,据此提出了药剂混用技术、PAM改性技术、改性PAM+药剂混用技术和PAM降解技术等,同时总结了PAM作用机理研究现状和相关研究方法,新的检测手段将不断完善PAM的作用机理。针对PAM在使用过程中容易出现的问题给出相应的策略,高效的药剂配置、自动添加技术以及正确的加药顺序等都是PAM精细化使用的有效手段。通过总结和梳理PAM在矿物加工领域的多种应用和策略,不仅对PAM的研究方向有重要意义,还对矿物加工技术的发展有积极地促进作用。