共查询到20条相似文献，搜索用时 31 毫秒
1.
D.F. Bagster 《International Journal of Mineral Processing》1985,14(1):21-32
Having previously established a system of hematite and silica which can be separated effectively using long-chain polyacrylamide flocculants (Part 1) a stirred tank system was chosen to enable physical variables of flocculant concentration, impeller speed, time of flocculation, slurry concentration, ratio of hematite to quartz in the feed and particle size distribution to be studied.It was concluded that the time of flocculation allowed should be kept short and that there is an optimum of impeller speed though not a sharp one. Slurry concentration must be kept to 1% w/w to prevent serious performance deterioration. A clear optimum flocculant concentration was not found under present circumstances though very low concentrations (< 1 ppm) gave poor results while high concentrations gave no improvement on the results at about 2 ppm.Comparison between an impeller and a propeller of the same diameter and location in the tank pointed to the possibility of critical agitation configurations and the need for caution in scaling up results.The grade of material settling from a selective aggregation process is heavily dependent on the particle size distributions of the mineral species. Larger flocculated minerals produce richer flocs. 相似文献
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B. Gururaj J.P. Sharma A. Baldawa S.C.D. Arora N. Prasad A.K. Biswas 《International Journal of Mineral Processing》1983,11(4):285-302
Studies have been made on the separability of clay minerals such as kaolinite, illite and montmorillonite from hematite in dispersant-starch flocculant systems. The grossly different dispersibility of hematite from that of clay minerals aided separation by selective dispersion and flocculation. Moderate success has been achieved with a selectivity index nearing 4.0 (average recovery values around 80%).The studies have been extended to hematite recovery and clay rejection from the slimes of the Barsua iron ore washing plant owned by Rourkela Steel Plant, India. Limited success achieved in the starch selective flocculation method has been attributed to the difficulties associated with fine grain size, clay mineraloty and liberation.The ore exhibits the phenomenon of differential grinding. Hematite-rich coarser particles in the slime can be separated by differential settling in dispersant systems followed by selective flocculation in low-starch systems. 相似文献
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This investigation has shown that quartz can be activated for polyacrylic acid adsorption by hydrolyzing metal cations, similar to activation in flotation. Detailed experiments on activation phenomena with ferric ions have been performed. The flocculation of activated quartz can be prevented by suitable additions of disodium EDTA, sodium hexametaphosphate or potassium fluoride. Selective flocculation of hematite with polyacrylic acid from a hematite/quartz mixture can be achieved in the pH range 3 to 9, but the process is not selective in the presence of ferric ions. Suitable additions of EDTA or KF are particularly successful in preventing quartz activation by ferric ions and the facilitating selective flocculation of hematite in artificial mixtures of quartz and hematite. 相似文献
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Zhang Rong-jun Zheng Yao-lin Zheng Jun-Jie Dong Chao-qiang Lu Zhan 《Acta Geotechnica》2020,15(6):1685-1698
A new method, i.e., flocculation–solidification combined method (FSCM), is proposed for building a working platform efficiently and economically at the surface of newly reclaimed ground filled with hydraulically dredged mud slurry at extra high water content (EHW-MS). A number of laboratory experiments are performed in this paper to identify the feasibility and mechanism of the proposed FSCM. First, the reasonable flocculant dosage range suitable for FSCM is determined by the simple sedimentation tests. Second, the engineering properties of FSCM, pure cement solidification method (PCSM) and pure flocculation conditioning method (PFCM) treated EHW-MS are compared in detail via a series of model tests, to demonstrate the superiority of FSCM over PCSM and the influence of flocculant dosage on FSCM efficiency. Third, the superiority of FSCM over PCSM is rationalized from the perspective of intrinsic working mechanism of flocculant and PCSM. Results demonstrate well that FSCM shows substantial superiority over PCSM, and at the reasonable flocculant dosage, the strength of FSCM-treated EHW-MS is at least 5.7 times larger than that of the corresponding PCSM-treated EHW-MS. The superiority of FSCM over PCSM can be attributed to two aspects, i.e., the dewatering effect and the other detrimental effect. The former is predominant and primarily governs the strength gain of FSCM-treated EHW-MS, while the latter is less significant but not negligible.
相似文献6.
The role of the presence of active groups in polymers and operating variables such as conditioning time in producing flocculation in single and mixed mineral slimes made of hematite, quartz and chalcopyrite is examined at different conditions of pH. Selective flocculation was achieved on the basis of results obtained for single mineral systems as, for example, in the case of hematite—quartz mixtures using sulfonated polymer. Flocculation was found to go through a maximum as the mineral was conditioned with the polymer solution. Interestingly, the times of maximum flocculation for various minerals were sufficiently different from each other so that it could be considered as a potential factor for achieving selectivity. Also, cleaning of the selectively flocculated product by simple redispersion in water improved the separation. Electrokinetic studies conducted to study the mechanisms involved provided indication for the shift of shear plane. 相似文献
7.
Solid–liquid separation of tailings slurries in gravity thickeners relies on the efficient mixing of slurry and dilute polymer flocculant solutions within the feedwell. Computational fluid dynamics (CFD) can provide predictions of solids distribution, liquor velocity and shear rate within a feedwell, and with the incorporation of an adsorption model, can also assess the effectiveness of flocculant mixing. This study presents the first use of feedwell CFD to examine the effect of the flocculant inlet direction and velocity on the subsequent distribution and adsorption of flocculant. When flocculant is injected inside the feed stream, a high inlet nozzle velocity will maximise adsorption, with injection preferably vertically upward or towards the feedwell walls. For injection inside the dilution stream (vertical upflow of liquor within the feedwell), the flocculant should be directed either upwards or inwards away from the strong downward flow of the feed stream, with the velocity not critical.At flocculant inlet velocities predicted by CFD to enhance mixing and adsorption, the shear rate experienced within the injection pipe exceeds that in the feedwell, and the duration under higher shear may be greater. Pipe flow studies for several flocculants have confirmed reductions in activity at a solution concentration of 0.025 wt.%; this effect diminishes with greater dilution. Much of this lost activity is recovered on standing, indicating that the applied shear leads to a mixture of chain scission (irreversible) and entanglement (reversible). Minimising the duration of such shear effects on flocculant solution transport to the feedwell is essential, as the potential for increased flocculant demand and reduced flocculation efficiency can easily exceed any benefit from improved feedwell mixing. 相似文献
8.
Yosry A. Attia 《International Journal of Mineral Processing》1983,10(3):173-181
One of the main usages of ball clays is in the pottery industry. However, in order to transport the clay suspensions from the mine site, some distance away from the consumer, dewatering of the clay suspension must be performed. The main restriction is that any dewatering treatment must not interfere in obtaining deflocculated, free flowing suspensions required by the pottery manufacturer.Investigations in the flocculation/deflocculation of these clay suspensions, resulted in finding a technique capable of achieving both requirements. The technique employs flocculation by an anionic flocculant in the presence of 10 mM of magnesium sulfate, thus achieving the dewatering step. When the magnesium sulfate was removed from the flocculated suspensions by simply washing the filter cake, good deflocculation of the clay suspension was achieved at alkaline pH. The role of MgSO4 in the flocculant adsorption/flocculation, and subsequently in the flocculant desorption/deflocculation, was discussed. 相似文献
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地下连续墙、水平定向钻、盾构和顶管等领域的基础工程浆液具有用量大、污染物较为单一的特点。随着国家各项环保法规的实施,基础工程浆液的综合处理尤为重要。提出一种基础工程浆液资源化综合利用技术,即循环浆液采用“除砂+净化浆液与钻渣综合利用”技术,废弃浆液采用“除钙+降低pH+絮凝分离+压滤处理+废液与泥饼的综合利用”技术。以武汉市某地下连续墙工程现场浆液为研究对象,研究循环浆液和废弃浆液的资源化综合利用效果。结果表明:(1) 循环浆液经过除砂后得到净化浆液和钻渣,前者可重新用于工程施工中,后者可用于培育披碱草、黑麦草等草籽,发芽率为100%。(2) 加入5%的碳酸氢钠可将废弃浆液Ca2+质量浓度从703.5 mg/L降低至173.6 mg/L,加入质量分数为3.3%的氯化铵可将pH值从13降低至9,加入300 mg/L的絮凝剂A-2可得到明显的絮凝物。絮凝物经过压滤后得到废液和泥饼,在废液中加入质量分数为2%的碳酸氢钠后可用于重新配制工程浆液,泥饼与30%~60%的营养土混合后可进行草籽培育,发芽率为72%。(3) 过量的盐离子和高pH会对植物生长产生毒害作用,应先对废弃浆液进行除钙和降低pH等处理,之后压滤得到的泥饼才能满足植物生长要求。该技术可实现基础工程浆液中所有钻渣(或泥饼)和净化后的浆液(或废液)的资源化综合利用,对类似工程浆液的资源化利用有较好的启示意义,具有显著的经济、环境和社会效益。 相似文献
10.
Polyacrylate and hydroxamate flocculants are commonly used to aid solid–liquid separation of bauxite residue from pregnant liquor in the Bayer process. This study presents the direct examination of the bauxite residue flocculation with polyacrylate and hydroxamate flocculants, using the focussed beam reflectance measurement (FBRM) probe to monitor aggregate dimensions.The key difference between polyacrylate and hydroxamate flocculation was found to be the way the aggregates developed post-shear, with hydroxamate flocculation exhibiting a greater degree of post-shear flocculation. Polyacrylate aggregates were found to be more dense and shear resistant, while the hydroxamate aggregates exhibited greater fines capture and lower solids in the supernatant. The solids remaining in the supernatant after flocculation were found to differ for each flocculant, with the polyacrylate system having relatively more coarse particles within the solid and the hydroxamate system being relatively finer and more iron rich. The observed results are discussed in terms of the different way in which each polymer is considered to adsorb onto the residue material. 相似文献
11.
Experiments have shown that it is possible to obtain a concentrate containing 65% iron, 1.8% alumina and 1.4% silica with an iron recovery of 80% from the tailings of Barsuan iron ore plant containing 52.5% iron, 7.4% alumina and 7.8% silica through selective flocculation employing starch. Key to such success lies in the manner in which the flocculant is desired from the parent starch. Barsuan deposit being a limiting case of typical fine-grained high-alumina iron ores, the results open up technical possibilities of better utilization of such deposits. 相似文献
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Hematite, as a typical iron oxide slime in sulphide ore slurries, was artificially added into the leaching systems of pure gold and a sulphide ore respectively, in an attempt to investigate the effect of iron oxide slimes on the ammoniacal thiosulphate leaching of gold. The presence of hematite significantly reduced the dissolution of gold and this detrimental effect became more pronounced with increasing hematite concentration. Hematite formed coatings on gold surfaces, which could prevent leach solution from diffusing to the gold surfaces and hence, inhibit gold dissolution. Hematite catalysed the oxidative decomposition of thiosulphate to polythionates with oxygen present. XPS studies indicated a thin layer of iron oxide coating as well as the deposition of some copper and sulphur species on gold surfaces. SEM images revealed a lesser extent of corrosion for gold after leaching in the presence of hematite. The gold extraction from the sulphide ore was reduced with the addition of hematite and this effect became more noticeable with an addition of hematite at a higher concentration. A natural guar type surfactant (Gempolym M47) reduced the detrimental effect of hematite on gold extraction likely due to the prevention of hematite coating on gold and mineral particles and the dispersion of the mineral slurry. Gempolym M47 stabilised thiosulphate by weakening the interaction between cupric ions and thiosulphate and by minimising the catalytic effect of hematite on thiosulphate decomposition. 相似文献
15.
Non-parallelism between the effect of microbial flocculants on sewerage disposal and the flocculation rate 总被引：2，自引：1，他引：2
1 IntroductionMicrobial flocculant (MBF) is one of the naturalmacromolecular organic compounds, which is producedby some microorganisms and has a high flocculationfunction ( Cheng Wen et al., 2003). It has beencalled“the third-generation flocculant”beca… 相似文献
16.
Y.A. Attia 《International Journal of Mineral Processing》1977,4(3):209-225
Problems encountered in developing a selective flocculation process for a complex copper ore and ways of overcoming these difficulties are reported. To obtain a useful enrichment ratio, multiple stages of flocculation and redispersion were found necessary in order to release entrapped, unwanted particles. Particular attention was given to the dispersion process of the ore suspensions, and the importance of mechanical and chemical factors were established. The effects of solids content and quality of water on the performance of selective flocculation have been investigated. The possibility of developing new, selective or more powerful dispersants was confirmed and one such reagent was tested. 相似文献
17.
This paper presents the results of investigation on uptake of radioactive species 90Sr and 137Cs present in the liquid effluents from nuclear processing plants. Chemical precipitation process is adopted to remove radioactivity from the effluents with low and intermediate level of activity. In this process, radioactive 90Sr and 137Cs are co-precipitated along with copper ferrocyanide, ferric hydroxide and either calcium phosphate or barium sulphate. These precipitates being fine in size require flocculation for enhanced settling rate in clarifier/thickener. The flocculation by some selected high molecular weight polyacrylamide based polymers has improved the uptake of radioactive metal ions. The adsorption of these radioactive species has been found to increase in the presence of these flocculants thereby improving the decontamination factor (DF). While flocculating the precipitates, there may be some complex formation with Sr2+/Cs+, flocculant and the substrate. This has enhanced the uptake of the radioactive metal ions from the liquid component. The plant trials have indicated the improvement of DF value due to flocculation by cationic flocculant. 相似文献
18.
David G. Osborne 《International Journal of Mineral Processing》1974,1(3):243-260
Polymer flocculants, whilst having a proven ability as settling and filtration aids, are relatively expensive additives and must therefore be selected and applied with careful consideration.When it appears possible to make reliable prediction of dosage requirement based upon some specific understanding of flocculant behaviour with a particular material, then such a prediction may further reduce the risk of incorrect selection and administration.This paper describes recent work conducted to examine the behaviour of coal slurries varying in ash content, when flocculated with a number of different flocculants. The objective of the work was to determine whether any common relationship existed between flocculant dosage requirement, and the proportions of coal-shale present in the slurry. However, the paper has been written not as an attempt to prescribe specific flocculant types but rather, to provide an indication of what is considered by the author as being a realistic approach towards the assessment of flocculant suitability for a particular mixture of coal and shale. 相似文献
19.
Study on the flocculability of metal ions by<Emphasis Type="Italic">Bacillus mucilaginosus</Emphasis> GY03 strain 总被引：1，自引：0，他引：1
This study deals with the flocculability of two types of metal ions by Bacillus macilaginosus GY03 Strain, with an emphasis on the influence of pH conditions, volume and time of flocculants produced by GY03 Strain on the adsorption of metal irons such as Pb^2 and Mn^2 and the capabilities of floceulants to adsorb metal ions of different concentrations. The results showed that microbial flocculants produced by Bacillus mucilaginosus GY03 Strain are highly capable of flocculating metal ions, but show different effectiveness with respect to the adsorption of Pb^2 and Mn^2 . In accordance with the experimental data and actual waste-water treatment conditions, the relevant regression equation of floeculation has been deduced, which has found some application in practice. The experimental results of this study demonstrated that microbial flocculants produced by Bacillus mucilaginosus can be used to treat metallic ion-containing waste water. In practical application the volume of microbial floceulants required and flocculation conditions should be taken into comprehensive consideration in accordance with the properties of metal ions, the composition of anions and the solubility of other metals, in combination with the cost and effectiveness of floceulants to be used. Floeeulant used in this experiment has the advantages of being applied over a wide range of pH values, small flocculant volume, and rapid speed of floeeulation. So this kind of flocculant is within excellent prospect of application. 相似文献
20.
Inrecentyears,withtherapiddevelopmentofindustrialeconomy ,wastewaterisdischargedinhugevolumeandtheaccumulationofheavymetalionsinsoilsandwatersourcesisspeededuprapidly .Asaresult,waterpollutionhasbecomeadailydeterioratingproblem .Heavymetalsareeasytoenterthefoodchain ,therebyconstitutingagreatthreattothehealthofanimalsandhu manbeings .Therefore,howtoeffectivelyhandleheavymetalpollutionhasbecomeacommonat tractionformankind .Theroutineheavymetaltreatmentmethodsaremainlythechemical,phys icalandphy… 相似文献